Answer: a) b) Nitrogen dioxide, also known as $NO_2$ , is the brown gas X.
On heating blue coloured powder of copper (II) nitrate in a boiling tube, copper oxide (black), oxygen gas and a brown gas X is formed
Give the characteristic tests for the following gases
a)
b)
Answer: a) Pass CO2 through limewater, which will turn the water milky in colour. A confirmation test for the presence of Carbon-di-oxide is carried out here. b) The smell of SO2 is one of its...
Give the characteristic tests for the following gases
c) d)
Answer: c) The oxygen test involves lighting a match stick in the presence of oxygen, which causes the match stick to burn even more brightly. d) Burning matchstick is brought close to H2 gas and...
What happens when a piece of (c) silver metal is added to copper sulphate solution? Write a balanced equation.
Answer: c)There will be no reaction when silver metal is added to Copper Sulphate solution because silver is a non-reactive metal.
What happens when a piece of
(a) zinc metal is added to copper sulfate solution?
(b) aluminum metal is added to dilute hydrochloric acid? Write a balanced equation.
Solution: A) When zinc is added to a solution of copper sulfate, zinc displaces copper and forms zinc sulphate as a result. Zn(s)+ CuSo4(aq)→ ZnSo4(aq)+ Cu(s) b) When aluminium metals react with...
What happens when zinc granules are treated with a dilute solution of , HCl, , NaCl and NaOH, also write the chemical equations if a reaction occurs.
Solution: Displacement reaction occurs when zinc granules react with concentrated H2SO4, resulting in the formation of ZnSO4 and the release of hydrogen gas. Zn( s)+ H2SO4(aq)→ ZnSo4 (aq)+H2 (g)...
On adding a drop of barium chloride solution to an aqueous solution of sodium sulfite, a white precipitate is obtained.
(c) On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?
Solution: c) When we add dilute $HCl$ to this reaction mixture, we get the following products: barium chloride, sulphur dioxide, and water. Due to the fact that barium chloride is a soluble...
On adding a drop of barium chloride solution to an aqueous solution of sodium sulfite, a white precipitate is obtained.
(a) Write a balanced chemical equation of the reaction involved
(b) What other name can be given to this precipitation reaction?
Solution: a)The reaction of a drop of Barium Chloride solution with one drop of sodium sulphite solution results in the formation of barium sulphite, a white precipitate of barium sulphite....
You are provided with two containers made up of copper and aluminum. You is also provided with solutions of dilute HCl, dilute , and . In which of the above containers these solutions can be kept?
Answer: Due to the fact that copper is a noble metal and will not react with HCl or even $HNO_3$, it is possible to store this solution in a copper container. Keeping the solution in an aluminium...
Which of the following ray diagrams is correct for the ray of light incident on a lens shown in the figure?
(a) Fig. A. (b) Fig. B. (c) Fig. C. (d) Fig. D. Answer: (a) Fig. A. Explanation: The ray diagram in figure A is correct for the light ray incident on a lens as the incident ray travels through the...
The path of a ray of light coming from air passing through a rectangular glass slab traced by four students are shown as A, B, C and D in the Figure. Which one of them is correct?
(a) A (b) B (c) C (d) D Answer: b) B Explanation: The path of a ray of light coming from air passing through a rectangular glass slab traced by the student B is correct.
A beam of light is incident through the holes on side A and emerges out of the holes on the other face of the box as shown in the figure. Which of the following could be inside the box?
(a) Concave lens (b) Rectangular glass slab (c) Prism (d) Convex lens Answer: (d) Convex lens Explanation: When a beam of light is incident through the holes on side A and emerges out of the holes...
Find out the following in the electric circuit given in Figure 12.9
(c) Potential difference across 4 Ω resistance
(d) Power dissipated in 4 Ω resistor (e) Difference in ammeter readings, if any
Solution: The potential difference across $4 \Omega$ resistor is potential drop by the $4 \Omega$ resistor.$V=I R=1 \times 4=4 V$The power dissipated in $4 \Omega$ resistor$$P=I^{2} R=1^{2} \times...
Find out the following in the electric circuit given in Figure 12.9
(a) Effective resistance of two 8 Ω resistors in the combination
(b) Current flowing through 4 Ω resistor
Solution: (a) Since, two $8 \Omega$ resistors are in parallel, then their effective resistance $R_{p}$ is given by$$\begin{aligned}\frac{1}{R_{p}}...
What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.
Solution: According to the Joules heating effect, the amount of heat that a resistor produces is For the given resistor, the voltage is directly proportional to the square of the current.Resistance...
How will you conclude that the same potential difference (voltage) exists across three resistors connected in a parallel arrangement to a battery?
Solution: Create a circuit with three resistors (R1, R2, and R3) connected in parallel, as shown in the diagram below: Take a reading of the potential difference between three resistors that are...
How will you infer with the help of an experiment that the same current flows through every part of the circuit containing three resistances in series connected to a battery?
Solution: To construct the circuit, connect three resistors R1, R2, and R3 in series.Make use of an ammeter to observe the changes that have occurred in the current flow.Remove R1 and measure the...
What is electrical resistivity of a material? What is its unit? Describe an experiment to study the factors on which the resistance of conducting wire depends.
Answer: The ability of a conductor to resist the flow of electric current is an inherent property of the conductor itself. Each material's resistance is distinct from the others. Resistance is...
State Ohm’s law? How can it be verified experimentally? Does it hold good under all conditions? Comment.
Answer: Ohm’s law states that at constant temperature potential difference (voltage) across an ideal conductor is proportional to the current through it. V/I = R Ohm's law is being checked for...
Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit, another set of three bulbs of the same wattage are connected in parallel to the same source.
(a) Will the bulb in the two circuits glow with the same brightness? Justify your answer.
(b) Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
Answer: a) In a series configuration, the resistance of the bulbs is three times greater than the resistance of a single bulb. As a result, when compared to the current in each bulb in the parallel...
B1 , B2, and B3 are three identical bulbs connected as shown in Figure 12.8. When all the three bulbs glow, a current of 3A is recorded by ammeter A.
What happens to the glow of the other two bulbs when the bulb B1 gets fused?
What happens to the reading of A1 , A2 , A3 and A when the bulb B2 gets fused?
Solution: In a parallel circuit, the potential difference does not become divided. As a result, when bulb one is fused, the glowing of the other bulbs will not be affected. 3 Amperes are being...
B1, B2, and B3 are three identical bulbs connected as shown in Figure 12.8. When all the three bulbs glow, a current of 3A is recorded by ammeter A. How much power is dissipated in the circuit when all the three bulbs glow together?
Solution: Evaluating the value, R= V/I = 4.5V/3A= 1.5Ω As we know that, substituting the value of parameters in P= I2R, we get = (3A)2 x 1.5 Ω = 13.5 W
Why is the parallel arrangement used in domestic wiring?
Answer: Parallel wiring is commonly used in domestic wiring because it ensures that the potential difference between each electrical appliance is the same across the board.
A current of 1 ampere flows in a series circuit containing an electric lamp and a conductor of 5 Ω when connected to a 10 V battery. Calculate the resistance of the electric lamp. Now if the resistance of 10 Ω is connected in parallel with this series combination, what change (if any) in current flowing through 5 Ω conductor and potential difference across the lamp will take place? Give reason.
Solution: Given: I= 1 A, V= 5 V 1) Let R be the resistance of the electric lamp. In series total resistance = 5 + R I = v/r 1 = 10/5+R R = 5 ohm 2) V across Lamp + conductor = 10 V V acoess Lamp =...
What is the commercial unit of electrical energy? Represent it in terms of joules.
Solution: Electrical energy is a term that is used to refer to energy that has been converted from electric potential energy when it is used informally. Commercial unit of electrical energy is...
What is electrical resistivity? In a series electrical circuit comprising a resistor made up of a metallic wire, the ammeter reads 5 A. The reading of the ammeter decreases to half when the length of the wire is doubled. Why?
Answer: The resistivity of a conductor is defined as the property of the conductor that prevents the flow of electric current. The resistance of a particular material is one-of-a-kind. Resistance is...
How does the use of a fuse wire protect electrical appliances?
Answer: The resistance of fuse wire is much higher than that of the main wiring. The electric current increases by a significant amount when this occurs. The fuse wire melts, causing the circuit to...
Draw a circuit diagram of an electric circuit containing a cell, a key, an ammeter, a resistor of 2 Ω in series with a combination of two resistors (4 Ω each) in parallel and a voltmeter across the parallel combination. Will the potential difference across the 2 Ω resistor be the same as that across the parallel combination of 4Ω resistors? Give reason.
Solution: The circuit diagram is: The following equation can be used to calculate the total resistance of a parallel combination of 40 resistors: $\frac{1}{R}=\frac{1}{4}+\frac{1}{4}=\frac{1}{2}$$R...
Should the resistance of an ammeter be low or high? Give reason.
Answer: The resistance of an ammeter should be low because the ammeter is connected in series with the circuit, and if the resistance of the circuit is too high, no current will flow through it.
Three 2 Ω resistors, A, B and C, are connected as shown in Figure 12.7. Each of them dissipates energy and can withstand a maximum power of 18W without melting. Find the maximum current that can flow through the three resistors?
Solution: We know that Current $P = I ^{2} R$ Evaluating the value,$$18 W = l ^{2} \times 2 \Omega \I ^{2}=18 W / 2 \Omega \ $$ =9 A I =3 AThis is the maximum current that can flow through the three...
A child has drawn the electric circuit to study Ohm’s law as shown in Figure 12.6. His teacher told that the circuit diagram needs correction. Study the circuit diagram and redraw it after making all corrections.
Solution: Specifically, the ammeter has been connected in parallel with the voltmeter, which is not the correct way to connect the two metres. The ammeter should be connected in series with the...
Unit of electric power may also be expressed as
(a) volt-ampere
(b) kilowatt-hour
(c) watt-second
(d) joule second
Solution: The answer is (a) volt-ampere The apparent power of an electrical circuit is measured in volt-amperes (VA), which is the unit of measurement. A watt-second (also spelled watt-second,...
Two resistors of resistance 2 Ω and 4 Ω when connected to a battery will have
(a) same current flowing through them when connected in parallel
(b) same current flowing through them when connected in series
(c) the same potential difference across them when connected in series
(d) different p
Solution: The answer is (b) same current flowing through them when connected in series When using a series combination, the current is not divided into branches because the resistor receives a...
An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?
(a) 1 A
(b) 2 A
(c) 4 A
(d) 5 A
Solution: The answer is (d) 5 A We know, P=V x I Substituting , 1000 w = 220v x I I =1000w/220v = 4.54 A = 5 A
In an electrical circuit, two resistors of 2 Ω and 4 Ω respectively are connected in series to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be
(a) 5 J
(b) 10 J
(c) 20 J
(d) 30 J
Solution: Answer is (c) 20 J Equivalent resistance of the circuit is R = 4+2 = 6Ω current, I= V/R = 6/6= 1A the heat dissipated by 4-ohm resistor is, H = I2Rt = 20J
In an electrical circuit, three incandescent bulbs A, B and C of rating 40 W, 60 W and 100 W respectively are connected in parallel to an electric source. Which of the following is likely to happen regarding their brightness?
(a) The brightness of all the bulbs will be the same
(b) The brightness of bulb A will be the maximum
(c) The brightness of bulb B will be more than that of A
(d) The brightness of bulb C will be less than that of B
Solution: Answer is (c) Brightness of bulb B will be more than that of A Due to the fact that the bulbs are connected in parallel, their combined resistance will be less than the arithmetic sum of...
The resistivity does not change if
(a) the material is changed
(b) the temperature is changed
(c) the shape of the resistor is changed
(d) both material and temperature are changed
Solution: Answer is (c) the shape of the resistor is changed We will be re-arranging the terms we will receive, =A/RlAs a result, the resistivity of the material will be determined by its area and...
If the current I through a resistor is increased by 100% (assume that temperature remains unchanged), the increase in power dissipated will be
(a) 100 %
(b) 200 %
(c) 300 %
(d) 400 %
Solution: Answer is (c) 300 % The amount of heat generated by a resistor is proportional to the square of the current flowing through it. As a result, when the current is doubled, the dissipation of...
A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances R1, R2 and R3 respectively (Figure.12.5). Which of the following is true?
(a) R1 = R2 = R3
(b) R1 > R2 > R3
(c) R3 > R2 > R1
(d) R2 > R3 > R1
Solution: The answer is (c) R3 > R2 > R1 Resistance is inversely proportional to the amount of current flowing through it. Because the highest resistance will result in the least amount of current...
A cylindrical conductor of length l and uniform area of cross section A has resistance R. Another conductor of length 2l and resistance R of the same material has an area of cross-section
(a) A/2
(b) 3A/2
(c) 2A
(d) 3A
Solution: Answer is (c) 2A Explanation: We are well aware of this. R is equal to (L/A). The resistance of a wire of length L is denoted byThe area of the cross-section is denoted by the letter A.The...
Which of the following represents voltage?
(a)Work done/ Current×Time
(b) Work done × Charge
(c)Workdone×TimeCurrent
(d) Work done × Charge × Time
Solution: The answer is a) Explanation: Electric potential is the work done per unit charge. Electric Potential=Charge Work Done Again, Charge=Current×Time...
What is the minimum resistance which can be made using five resistors each of 1/5 Ω?
(a) 1/5 Ω
(b) 1/25 Ω
(c) 1/10 Ω
(d) 25 Ω
Solution: Answer is (b) 1/25 Ω Explanation: When resistors are connected in series, the resistance is reduced to a minimum. 1/R = 5 + 5 + 5 +5 +5= 25 Ω R=1/25Ω
The proper representation of the series combination of cells (Figure 12.4) obtaining maximum potential is
(a) (i)
(b) (ii)
(c) (iii)
(d) (iv)
Solution: The answer is (a) (i) Explanation: The positive terminal of the next cell is direct across from the negative terminal of the previous cell in this arrangement.
Identify the circuit (Figure 12.3) in which the electrical components have been properly connected.
(a) (i)
(b) (ii)
(c) (iii)
(d) (iv)
Solution: The answer is (b) (ii) Explanation: For current to flow, an electrical circuit must be closed. An open circuit can result from improperly connected components. An ammeter measures the...
A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in 16 seconds would be roughly
(a)
(b)
(c)
(d)
Solution: Answer is (a) 1020 Given $: I =1 A , t =16 s , e =1.6 \times 10^{-19} C$ Step 1: The filament draws current from the power supply. $I =\frac{ Q }{ t }=\frac{ Ne }{ t } \quad ($ Since $Q =...
Electrical resistivity of a given metallic wire depends upon
(a) its length
(b) its thickness
(c) its shape
(d) nature of the material
Solution: The answer is (d) nature of the material The resistivity of a material is an inherent property of the material. As an intensive property, it does not scale with the system's size, even if...
In the following circuits (Figure 12.2), the heat produced in the resistor or combination of resistors connected to a 12 V battery will be
(a) same in all the cases
(b) minimum in case (i)
(c) maximum in case(ii)
(d) maximum in case(iii)
Solution: The answer is (c) maximum in case(ii) In this example, two transistors are connected in series. Because they are connected in parallel, the total resistance in figure (iii) will be less...
A cell, a resistor, a key, and ammeter are arranged as shown in the circuit diagrams of Figure12.1. The current recorded in the ammeter will be
(a) maximum in (i)
(b) maximum in (ii)
(c) maximum in (iii)
(d) the same in all the cases
Solution: The answer is (d) the same in all the cases Because there are no modifications to any of the circuits, the current in all of the circuits will be the same.
Draw an appropriate schematic diagram showing common domestic circuits and discuss the importance of fuse. Why is it that a burnt-out fuse should be replaced by another fuse of identical rating?
Solution: Schematic diagram showing common domestic circuits The Importance of the Fuse A fuse is a type of safety device that is used in both household wiring and electrical appliance design.The...
Describe the working of an AC generator with the help of a labeled circuit diagram. What changes must be made in the arrangement to convert it to a DC generator?
Solution: It is stated in Faraday's law of electromagnetic induction that whenever a conductor moves in an electromagnetic field, an electromagnetic field is induced across the conductor. If a close...
Explain the phenomenon of electromagnetic induction. Describe an experiment to show that a current is set up in a closed loop when an external magnetic field passing through the loop increases or decreases.
Solution: The experimental diagram of circuit is: Electromagnetic induction is a phenomenon that occurs when a magnetic field is changed in a closed circuit, resulting in the generation of an...
Draw a labelled circuit diagram of a simple electric motor and explain its working. In what way these simple electric motors are different from commercial motors?
Solution: The schematic diagram of the simple electric motor is: A BCD coil is a coil that is placed between the two poles of a permanent magnet to create a magnetic field. The coil is positioned in...
Describe the activity that shows that a current-carrying conductor experiences a force perpendicular to its length and the external magnetic field. How does Fleming’s left-hand rule help us to find the direction of the force acting on the current-carrying conductor?
Answer: Take a small aluminium rod (AB) and bend it in half (of about 5 cm). As shown in Fig. 1, you can suspend it horizontally from a stand by using two connecting wires. A strong horseshoe magnet...
Explain with the help of a labeled diagram the distribution of magnetic field due to a current through a circular loop. Why is it that if a current-carrying coil has n turns the field produced at any point is n times as large as that produced by a single turn?
Answer: Even in a current-carrying loop, the right-hand thumb rule is observed and followed. This demonstrates that magnetic field lines are present all around the conducting wire. However, because...
With the help of a labeled circuit diagram illustrating the pattern of field lines of the magnetic field around a current-carrying straight long conducting wire. How is the right-hand thumb rule useful to find the direction of the magnetic field associated with a current-carrying conductor?
Answer: A straight conductor carrying current is held in the right hand with the thumb pointing in the direction of the current, according to the right-hand thumb rule. The fingers of the right hand...
Why does a magnetic compass needle pointing North and South in the absence of a nearby magnet get deflected when a bar magnet or a current-carrying loop is brought near it. Describe some salient features of magnetic lines of field concept.
Answer:Current carrying loops act as bar magnets with associated lines of the field, which are represented by the arrows. As a result, the existing earth's magnetic field is altered, resulting in a...
What is the role of fuse, used in series with any electrical appliance? Why should a fuse with a defined rating not be replaced by one with a larger rating?
Answer: An electrical fuse is composed of a thin wire of short length that is composed of tin and lead in the proportion of 75:25 percent. When the current exceeds the specified limit, the fuse...
What is the difference between a direct current and an alternating current? How many times does AC used in India change direction in one second?
Answer: The direction of current in an alternating current will change constantly, whereas the direction of current in a direct current will not change. In India, the air conditioner changes...
What is the role of the two conducting stationary brushes in a simple electric motor?
Answer: In order to power the motor, the two conducting stationary brushes must make contact with the outer sides of the two halves of the split rings, which are both insulated and attached to the...
Name four appliances wherein an electric motor, a rotating device that converts electrical energy to mechanical energy, is used as an important component. In what respect motors are different from generators?
Answer: Fans, mixers, washing machines, and computers are just a few examples of devices in which an electric motor, a rotating device that converts electrical energy to mechanical energy, plays a...
What does the divergence of magnetic field lines near the ends of a current-carrying straight solenoid indicate?
Answer: In a current-carrying straight solenoid, the divergence of magnetic field lines near the ends indicates a decrease in the strength of the magnetic field near and beyond the ends of the...
Meena draws magnetic field lines of the field close to the axis of a current-carrying circular loop. As she moves away from the centre of the circular loop she observes that the lines keep on diverging. How will you explain her observation?
Answer: The magnetic field strength decreases as the distance between the two points decreases. It is indicated by a decrease in the degree of closeness of the lines of field in the image.
What does the direction of thumb indicate in the right-hand thumb rule? In what way this rule is different from Fleming’s left-hand rule?
Answer: In the right-hand rule, the thumb held by curled fingers indicates the direction of current, whereas in Fleming's left-hand rule, the force experienced by a current-carrying conductor placed...
It is established that an electric current through a metallic conductor produces a magnetic field around it. Is there a similar magnetic field produced around a thin beam of moving (i) alpha particles, (ii) neutrons? Justify your answer.
Solution: i) Due to the fact that they are positively charged, alpha particles serve to generate current in the direction of motion. ii) Because neutrons do not have any charge on them, they do not...
A magnetic compass shows a deflection when placed near a current-carrying wire. How will the deflection of the compass get affected if the current in the wire is increased? Support your answer with a reason.
Answer: As the deflection increases, so does the deflection. The strength of the magnetic field will be directly proportional to the amount of current that passes through the straight conductor, as...
AB is a current-carrying conductor in the plane of the paper as shown in Figure 13.7. What are the directions of magnetic fields produced by it at points P and Q? Given r1 > r2, where will the strength of the magnetic field be larger?
Solution: P puts you into the plane of paper, and Q takes you out of it. The strength of the magnetic field is greater at the point that is closer to the source, which is Q.
Under what conditions permanent electromagnet is obtained if a current-carrying solenoid is used? Support your answer with the help of a labeled circuit diagram.
Solution: It is necessary to meet the following conditions in order to obtain a permanent electromagnet from a current-carrying solenoid. Soft iron is used in a closed-circuit core.
A magnetic compass needle is placed in the plane of paper near point A as shown in Figure 13.6. In which plane should a straight current-carrying conductor be placed so that it passes through A and there is no change in the deflection of the compass? Under what condition is the deflection maximum and why?
Answer: In the plane of the paper itself, to be precise. The axis of the compass is vertical, and the magnetic field produced by the conductor is vertical as well. Because of this, it is not...
The most important safety method used for protecting home appliances from short-circuiting or overloading is
(a) earthing
(b) use of fuse
(c) use of stabilizers
(d) use of electric meter
Solution: Answer is (b) use of fuse An electrical fuse is composed of a thin wire of short length that is composed of tin and lead in the proportion of 75:25 percent. When the current exceeds the...
To convert an AC generator into DC generator
(a) split-ring type commutator must be used
(b) slip rings and brushes must be used
(c) a stronger magnetic field must be used
(d) a rectangular wire loop must be used
Solution: Answer is (a) split-ring type commutator must be used After each half-turn of the armature, a split-ring type commutator reverses the direction of the current flowing through it. This...
The strength of the magnetic field inside a long current carrying straight solenoid is
(a) more at the ends than at the centre
(b) minimum in the middle
(c) same at all points
(d) found to increase from one end to the other
Solution: Answer is (c) same at all points Magnetic field lines are parallel inside the solenoid. This indicates the existence of a strong magnetic field. As a result, the magnetic field is uniform...
A constant current flow in a horizontal wire in the plane of the paper from east to west as shown in Figure 13.5. The direction of the magnetic field at a point will be North to South
(a) directly above the wire
(b) directly below the wire
(c) at a point located in the plane of the paper, on the north side of the wire
(d) at a point located in the plane of the paper, on the south side of the wire
Solution: The answer is (b) directly below the wire We can determine the direction of the magnetic field beneath the wire by applying the right-hand thumb rule.
Choose the incorrect statement
(a) Fleming’s right-hand rule is a simple rule to know the direction of induced current
(b) The right-hand thumb rule is used to find the direction of magnetic fields due to current-carrying conductors
(c) The difference between the direct and alternating currents is that the direct current always flows in one direction, whereas the alternating current reverses its direction periodically
(d) In India, the AC changes direction after every 1/50 second
Solution: The answer is (d) In India, the AC changes direction after every 1/50 second In India, the alternating current frequency is 50 Hz. Each cycle, the direction changes twice, so that the...
In the arrangement shown in Figure 13.4, there are two coils wound on a non-conducting cylindrical rod. Initially, the key is not inserted. Then the key is inserted and later removed. Then
(a) the deflection in the galvanometer remains zero throughout
(b) there is a momentary deflection in the galvanometer, but it dies out shortly and there is no effect when the key is removed
(c) there are momentary galvanometer deflections that die out shortly; the deflections are in the same direction
(d) there are momentary galvanometer deflections that die out shortly; the deflections are in opposite directions
Solution: The answer is (d) there are momentary galvanometer deflections that die out shortly; the deflections are in opposite directions When the key is plugged in, the galvanometer shows...
Commercial electric motors do not use
(a) an electromagnet to rotate the armature
(b) effectively large number of turns of conducting wire in the current-carrying coil
(c) a permanent magnet to rotate the armature
(d) a soft iron core on which the coil is wound
Solution: Answer is (c) a permanent magnet to rotate the armature Electromagnets are used in place of permanent magnets in electric motors.
A uniform magnetic field exists in the plane of paper pointing from left to right as shown in Figure 13.3. In the field an electron and a proton move as shown. The electron and the proton experience
(a) forces both pointing into the plane of paper
(b) forces both pointing out of the plane of paper
(c) forces pointing into the plane of paper and out of the plane of paper, respectively
(d) force pointing opposite and along the direction of the uniform magnetic field respectively
Solution: Answer is (a) forces both pointing into the plane of the paper Explanation: The direction of an electron's motion is the polar opposite of the direction of an electric current. This will...
For a current in a long straight solenoid N- and S-poles are created at the two ends. Among the following statements, the incorrect statement is
(a) The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid
(b) The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil
(c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet
(d) The N- and S-poles exchange position when the direction of current through the solenoid is reversed
Solution: Answer is (c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet Because the solenoid behaves similarly...
For a current in a long straight solenoid N- and S-poles are created at the two ends. Among the following statements, the incorrect statement is
(a) The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid
(b) The strong magnetic field produced inside the solenoid can be used to magnetize a piece of a magnetic material like soft iron when placed inside the coil
(c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet
(d) The N- and S-poles exchange position when the direction of current through the solenoid is reversed
Solution: Answer is (c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet Explanation: Due to the fact that a...
A circular loop placed in a plane perpendicular to the plane of paper carries a current when the key is ON. The current as seen from points A and B (in the plane of the paper and on the axis of the coil) is anti-clockwise and clockwise respectively. The magnetic field lines point from B to A. The N-pole of the resultant magnet is on the face close to
(a) A
(b) B
(c) A if the current is small, and B if the current is large
(d) B if the current is small and A if the current is large
Solution: Answer is (a) A Explanation: The magnetic field will be directed from the south pole to the north pole. As a result of field lines pointing from point B to point A, point A is displaying...
Choose the incorrect statement from the following regarding magnetic lines of the field
(a) The direction of the magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle points
(b) Magnetic field lines are closed curves
(c) If magnetic field lines are parallel and equidistant, they represent zero-field strength
(d) The relative strength of the magnetic field is shown by the degree of closeness of the field lines
In the case of open magnetic field lines drawn over the horizontal plane ABCD, the magnetic field lines will take the shape of concentric circles, with the centre of each circle located at the axis...
A light ray enters from medium A to medium B as shown in the Figure. The refractive
index of medium B relative to A will be (a) greater than unity (b) less than unity (c) equal to unity (d) zero Answer: (a) greater than unity Explanation: The refractive index is the bending of a...
Under which of the following conditions a concave mirror can form an image larger than the actual object?
(a) When the object is kept at a distance equal to its radius of curvature (b) When an object is kept at a distance less than its focal length (c) When an object is placed between the focus and...
A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is
(a) – 30 cm (b) – 20 cm (c) – 40 cm (d) – 60 cm Answer: (b) – 20 cm Explanation: In this case, the focal length of the concave mirror is – 20 cm.
Choose the incorrect statement from the following regarding magnetic lines of the field
(a) The direction of the magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle points
(b) Magnetic field lines are closed curves
(c) If magnetic field lines are parallel and equidistant, they represent zero-field strength
(d) The relative strength of the magnetic field is shown by the degree of closeness of the field lines
Answer is (c) If magnetic field lines are parallel and equidistant, they represent zero-field strength Explanation: Due to the fact that parallel lines of magnetism represent a homogenous magnetic...
Explain the phenomenon of dispersion of white light through a glass prism, using a suitable ray diagram.
Answer: When a ray of light enters a prism, it bends because of refraction of light. When the ray of light finally emerges out of the prism. it deviates drastically from its original path. This...
How can we explain the reddish appearance of the sun at sunrise or sunset? Why does it not appear red at noon?
Answer: The sun appears red at sunrise and sunset because the sun is closer to the horizon during these times of the year. During its journey to our eyes, sunlight passes through a denser layer of...
Explain the refraction of light through a triangular glass prism using a labelled ray diagram. Hence define the angle of deviation.
The refraction of light through a triangular glass prism is depicted in the illustration above. At the first surface AB, a beam of light PE is penetrating the glass from the surrounding air. Due to...
When do we consider a person to be myopic or hypermetropic? Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected?
Answer: Myopia is a condition in which a person's ability to see distant objects clearly is impaired. Myopia is a condition in which the image is created in front of the retina rather than behind...
Explain the structure and functioning of the human eye. How are we able to see nearby as well as distant objects?
Answer: The human eye is considered to be one of the most valuable and sensitive sense organs on the planet. It allows us to take in the beauty of the world and the colours that surround us. After...
What is the difference in colours of the Sun observed during sunrise/sunset and noon? Give an explanation for each.
Answer: The sun appears red at sunrise and sunset because the sun is closer to the horizon during these times of the year. During its journey to our eyes, sunlight passes through a denser layer of...
Why is the colour of the clear sky blue?
Answer: The colour blue is the one that scatters the most light in the visible spectrum, and it is the most intense. As a result, the blue colour is able to reach us and the sky appears to be blue.
Why do we see a rainbow in the sky only after rainfall?
Answer: Rainbows are generated by the dispersion of sunlight by microscopic water droplets in the atmosphere, which are present in the air. A rainbow is always generated in the opposite direction to...
Is the position of a star as seen by us its true position? Justify your answer.
Answer: When starlight enters the earth's atmosphere, it is subjected to constant refraction. Refraction happens in a material with a refractive index that is gradually changing. Starlight is...
Draw a ray diagram showing the dispersion through a prism when a narrow beam of white light is incident on one of its refracting surfaces. Also indicate the order of the colours of the spectrum obtained.
Solution: The ray diagram is:
How will you use two identical prisms so that a narrow beam of white light incident on one prism emerges out of the second prism as white light? Draw the diagram.
Solution: Using two identical prisms that are inverted with regard to one another, we can create a narrow beam of white light that is incident on one prism and emerges out of the second prism as...
A person needs a lens of power –4.5 D for correction of her vision. (c) What is the nature of the corrective lens?
Answer: Myopia is a condition in which a pupil is unable to see the chalkboard that is far away from her. As a result, the doctor recommends a concave lens with a proper focal length. Negative sign...
A person needs a lens of power –4.5 D for correction of her vision.
(a) What kind of defect in vision is she suffering from?
(b) What is the focal length of the corrective lens?
Solution: Myopia is a condition in which a pupil is unable to see the chalkboard that is far away from her. As a result, the doctor recommends a concave lens with a proper focal length. Answer is...
How are we able to see nearby and also the distant objects clearly?
Answer: By varying the focal length of the lens, we can make our eyes focus on images from a variety of different distances. The action of the Ciliary muscle aids in the adjustment of the focal...
A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her? Draw ray diagram for the correction of this defect.
Myopia is a condition in which a pupil is unable to see the chalkboard that is far away from her. As a result, the doctor recommends a concave lens with a proper focal length.
Draw ray diagrams each showing (i) myopic eye and (ii) hypermetropic eye.
Solution: Myopia is a condition in which a person's ability to see distant objects clearly outweighs his ability to perceive those closer to him. Hypermetropia is a condition in which a person...
Which of the following statement is correct?
(a) A person with myopia can see distant objects clearly
(b) A person with hypermetropia can see nearby objects clearly
(c) A person with myopia can see nearby objects clearly
(d) A person with hypermetropia cannot see distant objects clearly
Solution: Answer is (c) A person with myopia can see nearby objects clearly Myopia is a condition in which a person's ability to see distant objects clearly outweighs his ability to perceive those...
The focal length of the eye lens increases when eye muscles
(a) are relaxed and the lens becomes thinner
(b) contract and lens become thicker
(c) are relaxed and the lens becomes thicker
(d) contract and lens become thinner
Solution: Answer is (a) are relaxed and the lens becomes thinner When the eye muscles relax and become thinner, the focal length of the eye lens grows in proportion to its thickness. The retina is...
When light rays enter the eye, most of the refraction occurs at the
(a) crystalline lens
(b) outer surface of the cornea
(c) iris
(d) pupil
Solution: The answer is (b) the outer surface of the cornea The cornea is a thin membrane that allows light to pass through to the eye. When light rays strike the cornea, they are bent inward and...
The bluish colour of water in the deep sea is due to
(a) the presence of algae and other plants found in water
(b) reflection of sky in water
(c) scattering of light
(d) absorption of light by the sea
Solution: The answer is (b) reflection of sky in water Explanation: Water is colourless, but it takes on the colour of whatever it is reflected by. As a result, the sea seems blue.
Which of the following phenomena contributes significantly to the reddish appearance of the sun at sunrise or sunset?
(a) Dispersion of light
(b) Scattering of light
(c) Total internal reflection of light
(d) Reflection of light from the earth
Solution: The answer is (b) Scattering of light Explanation: Because red scatters the least amount of light, it may go a long distance. When the sun sets or rises, light has to travel a long...
The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light
(a) is scattered the most by smoke or fog
(b) is scattered the least by smoke or fog
(c) is absorbed the most by smoke or fog
(d) moves fastest in air
Solution: The answer is (b) is scattered the least by smoke or fog Because the wavelength of red colour is the longest, it may be seen clearly from a long distance. It is the colour that is least...
Which of the following statements is correct regarding the propagation of light of different colours of white light in air?
(a) Red light moves fastest
(b) Blue light moves faster than green light
(c) All the colours of the white light move with the same speed
(d) Yellow light moves with the mean speed as that of the red and the violet light
Solution: The correct option is C All of the colours in the white light travel at the same speed as one another. Because air is not a dispersive medium, light of all wavelengths travels at the same...
Twinkling of stars is due to atmospheric
(a) dispersion of light by water droplets
(b) refraction of light by different layers of varying refractive indices
(c) scattering of light by dust particles
(d) internal reflection of light by clouds
Solution: The answer is (b) refraction of light by different layers of varying refractive indices Explanation: The refraction of light maintains the change in the position of the source of light....
The clear sky appears blue because
(a) blue light gets absorbed in the atmosphere
(b) ultraviolet radiations are absorbed in the atmosphere
(c) violet and blue lights get scattered more than lights of all other colors by the atmosphere
(d) light of all other colors is scattered more than the violet and blue color lights by the atmosphere
Solution: Answer is (c) violet and blue lights get scattered more than lights of all other colors by the atmosphere. Rayleigh's scattering of sunlight is responsible for the blue appearance of the...
At noon the sun appears white as
(a) light is least scattered
b) all the colours of the white light are scattered away
(c) blue colour is scattered the most
(d) red colour is scattered the most
Solution: The answer is (b) all the colours of the white light are scattered away This is due to the dispersion of light caused by the presence of air in the environment.
Which of the following phenomena of light are involved in the formation of a rainbow?
(a) Reflection, refraction, and dispersion
(b) Refraction, dispersion, and total internal reflection
(c) Refraction, dispersion, and internal reflection
d) Dispersion, scattering and total internal reflection
Solution: Answer is (c) Refraction, dispersion, and internal reflection Dispersion of light results in the scattering of white light into multiple colours at different angles, resulting in internal...
A prism ABC (with BC as a base) is placed in different orientations. A narrow beam of white light is incident on the prism as shown in Figure 11.1. In which of the following cases, after dispersion, the third colour from the top corresponds to the colour of the sky? The Human Eye and the Colourful World CHAPTER11 Fig.11.1
(a) (i)
(b) (ii)
(c) (iii)
(d) (iv)
Solution: The answer is (b) (ii) If the prism is kept with BC at the bottom, a band of colour appears at the bottom that is violet. If the prism is kept with BC at the top, violet will be at the top...
A student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his textbook. Which of the following statements is correct?
(a) The near point of his eyes has receded away
(b) The near point of his eyes has come closer to him
(c) The far point of his eyes has come closer to him
(d) The far point of his eyes has receded away
Solution: Answer is (a) The near point of his eyes has receded away In hypermetropia, the near spot of the eye is moved away for 25 cm. Thus, in order to read properly, the user needs maintain the...
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power
(a) + 0.5 D
(b) – 0.5 D
(c) + 0.2 D
(d) – 0.2 D
Solution:The answer is (b) – 0.5 D Because the individual is myopic and in need of a concave mirror, the power would be in the negative. P=1/f=1/2m=0.5 D.
An element X of group 15 exists as a diatomic molecule and combines with hydrogen at 773 K in presence of the catalyst to form a compound, ammonia which has a characteristic pungent smell.
(a) Identify the element X. How many valence electrons does it have?
(b) Draw the electron dot structure of the diatomic molecule of X. What type of bond is formed in it?
Solution: Nitrogen is the correct answer, as it possesses five electrons in its outermost shell.
An element X of group 15 exists as a diatomic molecule and combines with hydrogen at 773 K in presence of the catalyst to form a compound, ammonia which has a characteristic pungent smell.
(c) Draw the electron dot structure for ammonia and what type of bond is formed in it?
Solution: Covalent bonding is formed by ammonia.
An element X which is a yellow solid at room temperature shows catenation and allotropy. X forms two oxides which are also formed during the thermal decomposition of ferrous sulphate crystals and are the major air pollutants.
(e) Locate the position of the element in the Modern Periodic Table
Solution: The position of sulfur is Group 16 Period 3.
An element X which is a yellow solid at room temperature shows catenation and allotropy. X forms two oxides which are also formed during the thermal decomposition of ferrous sulphate crystals and are the major air pollutants.
(c) Write the balanced chemical equation for the thermal decomposition of ferrous sulphate crystals?
(d) What would be the nature (acidic/ basic) of oxides formed?
Solution: 2FeSO4 Fe2O3+SO2+SO3Sulphur oxides are acidic in nature
An element X which is a yellow solid at room temperature shows catenation and allotropy. X forms two oxides which are also formed during the thermal decomposition of ferrous sulphate crystals and are the major air pollutants.
(a) Identify the element X
(b) Write the electronic configuration of X.
Solution: Element X is Sulphur2,8,6
Electropositive nature of the element(s) increases down the group and decreases across the period
(b) Electronegativity of the element decreases down the group and increases across the period
(c) Atomic size increases down the group and decreases across a period (left to right)
(d) Metallic character increases down the group and decreases across a period.
Based on the above trends of the Periodic Table, answer the following about the elements with atomic numbers 3 to 9.
(c) Name the element with the smallest atomic size
(d) Name the element which is a metalloid
Solution: (a)The electropositive character of the element(s) increases as it progresses through the group and diminishes as it progresses through time. (b) The element's electronegativity drops as...
Electropositive nature of the element(s) increases down the group and decreases across the period
(b) Electronegativity of the element decreases down the group and increases across the period
(c) Atomic size increases down the group and decreases across a period (left to right)
(d) Metallic character increases down the group and decreases across a period.
Based on the above trends of the Periodic Table, answer the following about the elements with atomic numbers 3 to 9.
(e) Name the element which shows maximum valency.
Solution: (a)The electropositive character of the element(s) increases as it progresses through the group and diminishes as it progresses through time. (b) The element's electronegativity drops as...
Electropositive nature of the element(s) increases down the group and decreases across the period
(b) Electronegativity of the element decreases down the group and increases across the period
(c) Atomic size increases down the group and decreases across a period (left to right)
(d) Metallic character increases down the group and decreases across a period.
Based on the above trends of the Periodic Table, answer the following about the elements with atomic numbers 3 to 9.
(a) Name the most electropositive element among them
(b) Name the most electronegative element
Solution: (a)The electropositive character of the element(s) increases as it progresses through the group and diminishes as it progresses through time. (b) The element's electronegativity drops as...
Mendeleev ′ predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.
(c) Classify these elements as metals, non-metals, or metalloids
(d) How many valence electrons are present in each one of them?
Solution: c) Gallium-Group 13 Period 4 is a periodic table of elements. The elements germanium and gallium are both metalloids; however, gallium is a metal. d) Germanium contains four electrons, but...
Mendeleev ′ predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.
(a) Name the elements which have taken the place of these elements
(b) Mention the group and the period of these elements in the Modern Periodic Table.
Solution: a) Eka-Silicon was replaced by germanium, while Eka-Aluminum was replaced by gallium. b) Gallium was replaced by germanium. b) Germanium-Group 14 Period 4 (Germanium-Group 14).
(a) In this ladder (Figure 5.2) symbols of elements are jumbled up. Rearrange these symbols of elements in the increasing order of their atomic number in the Periodic Table.
(b) Arrange them in the order of their group also.
Solution: a) H, He, Li, Be, B, C, N, O, F, Ne, Mg, Al Si, P, S, Cl, Ar, K, Ca b) Group 1:H, Li, Na, K Group 2: Be, Mg, Ca Group 13: B. Al Group 14: C, Si Group 15: N. P Group 16: 0, S Group 17: F. U...
Complete the following crossword puzzle in figure:
Across:
(1) An element with atomic number 12.
(3) Metal used in making cans and member of Group 14.
(4) A lustrous non-metal which has 7 electrons in its outermost shell.
Down:
(2) Highly reactive and soft metal which imparts yellow colour when subjected to flame and is kept in kerosene.
(5) The first element of the second Period
(6) An element which is used in making fluorescent bulbs and is the second member of Group 18 in the Modern Periodic Table
(7) A radioactive element which is the last member of the halogen family.
(8) Metal which is an important constituent of steel and forms rust when exposed to moist air.
(9) The first metalloid in Modern Periodic Table whose fibres are used in making bullet-proof vests
Solution: Across 1) Magnesium 3) Tin 4) Iodine Down 2) Sodium 5) Lithium 6) Neon 7) Astatine 8) Iron 9) Boron
Atomic number of a few elements are given below 10, 20, 7, 14
(c) Identify the Periods of these elements in the Periodic Table
(d) What would be the electronic configuration for each of these elements?
Solution: (c)Nitrogen and Neon belong to period 2. Calcium and silicon belongs to Period 3. (d)Electronic Configurations Neon-2,8 Calcium-2,8,8,2 Nitrogen-2,5 Silicon-2,8,4
Atomic number of a few elements are given below 10, 20, 7, 14
(e) Determine the valency of these elements
Solution: During the formation of chemical compounds or molecules, an element's valence or valency is measured in terms of its ability to combine with other atoms, which is known as its combining...
Atomic number of a few elements are given below 10, 20, 7, 14
(a) Identify the elements
Solution: (a)Elements are Neon (10) Calcium (20) Nitrogen (7) Silicon (14) (b)Neon belongs to group 18, Calcium belongs to group 2, Nitrogen belongs to group 7 and Silicon belongs to group 14.
An element X (atomic number 17) reacts with an element Y (atomic number 20) to form a divalent halide.
(a) Where in the periodic table are elements X and Y placed?
(b) Classify X and Y as metal (s), non-metal (s) or metalloid (s)
Solution: The answer of the following is: (a)X is in Group 17, period 3 and Y is in group 2 Period 4. (b)X is Non-metal and Y is metal
An element X (atomic number 17) reacts with an element Y (atomic number 20) to form a divalent halide.
(c) What will be the nature of oxide of element Y? Identify the nature of bonding in the compound formed
(d) Draw the electron dot structure of the divalent halide.
Solution: c) Y Oxide will be a fundamental element in nature. Ionic bonding results in the formation of a compound. d) The electron dot structure:
An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.
(c) Write the balanced equation when it burns in the presence of air
(d) Write a balanced equation when this oxide is dissolved in water.
Solution: The answer: (c) 2Mg+O2 $\to$ 2MgO (d) MgO+ H2O $\to$ Mg(OH)2
An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.
(e) Draw the electron dot structure for the formation of this oxide
Solution: Lewis structures, also known as Lewis dot formulas, Lewis dot structures, electron dot structures, or Lewis electron dot structures, are diagrams that depict the bonding between atoms in a...
An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.
(a) Identify the element
(b) Write the electronic configuration.
Solution: The answer is: (a) Element is Magnesium (b) Electronic Configuration-2,8,2
Properties of the elements are given below. Where would you locate the following elements in the periodic table?
An element whose thin oxide layer is used to make other elements corrosion-resistant by the process of “anodising”
Solution: The answer is Aluminium Group 13 Period 3
Properties of the elements are given below. Where would you locate the following elements in the periodic table?
(1) An element which is tetravalent and forms the basis of organic chemistry
(2) An element which is an inert gas with atomic number 2
Solution: The answer of the following: Carbon Group 14 Period 2Helium Group 18 Period 1
Properties of the elements are given below. Where would you locate the following elements in the periodic table?
(a) A soft metal stored under kerosene
(b) An element with variable (more than one) valency stored underwater.
Solution: The answer for the following are: Sodium Group 1 Period 3Phosphorus Group 15 Period 3
Give an account of the process adopted by Mendeleev ′ for the classification of elements. How did he arrive at “Periodic Law”?
Solution: Only 63 elements were known at the time of Mendeleev's discovery. Mendeleev looked into the relationship between chemical characteristics and the atomic manes of elements in the periodic...
Which group of elements could be placed in Mendeleev’s ′ Periodic Table without disturbing the original order? Give reason.
Solution: Inert gases could be included in Mendeleev's Periodic Table without causing any disruptions to the original order of elements. Noble gases, such as Helium, were known prior to Mendeleev's...
Identify the elements with the following property and arrange them in increasing order of their reactivity
(a) An element which is a soft and reactive metal
(b) The metal which is an important constituent of limestone
(c) The metal which exists in a liquid state at room temperature
Solution: (a) Sodium (b) Calcium (c) Mercury and order of reactivity : Hg < Ca < Na
Arrange the following elements in the increasing order of their metallic character Mg, Ca, K, Ge, Ga.
Solution: The arrangement in order required is Ge < Ga < Mg < Ca < K
Write the formula of the product formed when the element A (atomic number 19) combines with the element B (atomic number 17). Draw its electronic dot structure. What is the nature of the bond formed?
Solution: The letter K represents element A. (Potassium). It would be possible to have the electrical configuration of element A (atomic number 19) as 2, 8, 8, 1. Because it has only one valence...
Identify and name the metals out of the following elements whose electronic configurations are given below.
(a) 2, 8, 2
(b) 2, 8, 1
(c) 2, 8, 7
(d) 2, 1
Solution: The names of the following are: MagnesiumSodiumChlorineLithium Metals from the following are- Magnesium, Sodium, Lithium.
Arrange the following elements in increasing order of their atomic radii.
(a) Li, Be, F, N
(b) Cl, At, Br I
Solution: The elements in question are all members of the same group and are sorted from left to right. As a result, their atomic radii are increasing in order of magnitude. a)Li>Be>F>N b)...
Compare the radii of two species X and Y. Give reasons for your answer.
(a) X has 12 protons and 12 electrons
(b) Y has 12 protons and 10 electrons
Solution: From electron arrangement X -2, 8, 2 Y -2, 8 Because Y has fewer energy levels than X, the atomic radius of Y will be less than that of the latter.
Three elements A, B and C have 3, 4 and 2 electrons respectively in their outermost shell. Give the group number to which they belong in the Modern Periodic Table. Also, give their valencies.
Solution: A belongs to Group 13, B belongs to Group 14, and C belongs to Group 2. A belongs to Group 13 and B belongs to Group 14. The values of A, B, and C are 3, 4, and 2, respectively.
Write the formulae of chlorides of Eka-silicon and Eka-aluminium, the elements predicted by Mendeleev.
Solution: Eka-silicon is a kind of germanium (Ge). It belongs to group 4 of Mendeleev's periodic table, and as a result, it has a valency of four. GeCl4 is the chemical formula for its chloride....
In Mendeleev’s Periodic Table the elements were arranged in the increasing order of their atomic masses. However, cobalt with an atomic mass of 58.93 amu was placed before nickel having an atomic mass of 58.71 amu. Give a reason for the same.
Solution: It is possible to find instances in Mendeleev ′s Periodic Table in which elements with higher atomic masses are put before ones with lower atomic masses, and vice versa. As a result, items...
“Hydrogen occupies a unique position in Modern Periodic Table”. Justify the statement.
Solution: Because of the following factors, hydrogen holds a unique place in the Modern Periodic Table. The outer electronic configuration of hydrogen and alkali metals is comparable because both...
Can the following groups of elements be classified as Dobereiner’s triad?
(a) Na, Si, Cl
(b) Be, Mg, Ca
The atomic mass of Be 9; Na 23; Mg 24; Si 28; Cl 35; Ca 40 Explain by giving a reason.
Solution: Despite the fact that the atomic mass of Silicon is equal to the average of the atomic masses of Sodium and Chlorine, the elements do not have the same physical properties and hence cannot...
Elements have been arranged in the following sequence on the basis of their increasing atomic masses. F, Na, Mg, Al, Si, P, S, Cl, Ar, K (a) Pick two sets of elements which have similar properties. (b) The given sequence represents which law of classification of elements?
Solution: a) Metals include sodium, magnesium, aluminum, and potassium. Halogens include the elements F and Cl. There are two sets of elements in total.b) Mendeleev's law of periodicity is...
The three elements A, B and C with similar properties have atomic masses X, Y and Z respectively. The mass of Y is approximately equal to the average mass of X and Z. What is such an arrangement of elements called as? Give one example of such a set of elements.
Solution: Triads are a type of arrangement of elements that is commonly found in nature. For example, the elements lithium, sodium, and potassium form a trio. These elements have atomic masses of...
On moving from left to right in a period in the periodic table, the size of the atom.
(a) increases
(b) decreases
(c) does not change appreciably
(d) first decreases and then increases
Solution: The answer is (b) decreases Explanation: When we move from left to right in a period, the radius of the atom shrinks, and as a result, the size of the atom reduces as well.
Which one of the following does not increase while moving down the group of the periodic table?
(a) Atomic radius
(b) Metallic character
(c) Valence
(d) Number of shells in an element
Solution: The answer is (c) Valence Explanation: In the periodic table, advancing down a group does not result in an increase in the number of valence electrons present.
Which one of the following depicts the correct representation of the atomic radius(r) of an atom?
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Solution: The answer is (b) (ii) and (iii) Explanation: Atomic radius, which is defined as the distance between the nucleus and the outermost orbital, is clearly displayed in photos ii) and iii),...
The element with atomic number 14 is hard and forms acidic oxide and a covalent halide. To which of the following categories does the element belong?
(a) Metal
(b) Metalloid
(c) Non-metal
(d) Left-hand side element
Solution: The answer is (b) Metalloid Explanation: Silicon has an electrical configuration of 2, 8, and 4 atoms. Considering that the outermost shell has just four electrons, it requires an...
Which of the following elements will form an acidic oxide?
(a) An element with atomic number 7
(b) An element with atomic number 3
(c) An element with atomic number 12
(d) An element with atomic number 19
Solution: The answer is (a) An element with atomic number 7 Explanation: The element with atomic number 7 has electron configuration 2,5, which means it has the ability to gain three electrons and...
Three elements B, Si and Ge are
(a) metals
(b) non-metals
(c) metalloids
(d) metal, non-metal, and metalloid respectively
Solution: The answer is (c) metalloids Explanation: Metalloids include the elements boron (B), silicon (Si), and germanium (Ge). Arsenic (As), antimony (Sb), tellurium (Te), polonium (Po), and...
What type of oxide would Eka– aluminium form?
(a)
(b)
(c)
(d) EO
Solution: Answer is (c) E2O3 Explanation: Aluminum is Al with an oxidation state of +3, it may be converted into Al3+, and it has a valency of +3. $Al_2O_3$ will be formed as a result.Gallium and...
Arrange the following elements in the order of their increasing non-metallic character Li, O, C, Be, F
(a) F < O < C < Be < Li
(b) Li < Be < C < O< F
(c) F < O < C < Be < Li
(d) F < O < Be < C < Li
Solution: The answer is b) Explanation: Li is located on the left side of the current periodic table in the second period, followed by berrylium. Fluorine is located directly across from Neon. As a...
Arrange the following elements in the order of their decreasing metallic character Na, Si, Cl, Mg, Al
(a) Cl > Si >Al > Mg >Na
(b) Na >Mg >Al >Si > Cl
(c) Na > Al > Mg > Cl > Si
(d) Al > Na> Si > Ca> Mg
Solution: The answer is (b) Na >Mg >Al >Si > Cl Explanation: Na has one electron in its valence shell, magnesium has two, aluminium has three, and chlorine has seven electrons in its valence shell....
Which of the following are the characteristics of isotopes of an element?
(i) Isotopes of an element have the same atomic masses
(ii) Isotopes of an element have the same atomic number
(iii) Isotopes of an element show the same physical properties
(iv) Isotopes of an element show the same chemical properties
(a) (i), (iii) and (iv)
(b) (ii), (iii) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)
Solution: Option d) is the answer. Explanation: Isotopes are elements that have the same atomic number but have different atomic masses, and they are classified as such. Isotopes have the same...
Which of the following elements does not lose an electron easily?
(a) Na
(b) F
(c) Mg
(d) Al
Solution: Option b) is the answer Explanation: Sodium has one electron, magnesium has two, and aluminum has three electrons in its outermost shell, whereas fluorine has seven electrons in its...
Which of the following elements would lose an electron easily?
(a) Mg
(b) Na
(c) K
(d) Ca
Solution: The answer is (c) K Explanation: Magnesium and calcium are both members of the group I, while sodium and potassium are members of a different group (II). Given that K has only one electron...
Which among the following elements has the largest atomic radii?
(a) Na
(b) Mg
(c) K
(d) Ca
Solution: The answer is (c) K Explanation: Because atomic radii decrease from left to right during a period of time, K has the biggest atomic radii of all the elements. This is due to an increase in...
Which of the following gives the correct increasing order of the atomic radii of O, F and N?
a) O, F, N
(b) N, F, O
(c) O, N, F
(d) F, O, N
Solution: The answer is (d) F, O, N Explanation: As you move from left to right over a period, the radius of an atom grows. The atomic numbers (N7), O(8), and F(10) are listed in increasing sequence...
Which one of the following elements exhibit a maximum number of valence electrons?
(a) Na
(b) Al
(c) Si
(d) P
Solution:The answer is (d) P Explanation: The electronic configurations of Na, Al, Si, and P are 2,8,1, 2,8,3,2,8,4, and 2,8,5 for the elements in the periodic table. The number of valence electrons...
Which of the following is the outermost shell for elements of period 2?
(a) K shell
(b) L shell
(c) M shell
(d) N shell
Solution: The answer is (b) L shell Explanation: There are two shells in period 18, designated as K and L.
An element which is an essential constituent of all organic compounds belongs to
(a) group 1
(b) group 14
(c) group 15
(d) group 16
Solution: The answer is b) group 14 Explanation: Carbon is an essential ingredient of all organic molecules that are members of the 14th chemical group.
Where would you locate the element with electronic configuration 2,8 in the Modern Periodic Table?
(a) Group 8
(b) Group 2
(c) Group 18
(d) Group 10
Solution: The answer is (c) Group 18 Explanation: Because group 18 has all of its outermost shells entirely filled, any element having an electrical configuration falls into this category.
The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively. Which pair of elements belong to the same group?
(a) A and B
(b) B and D
(c) A and C
(d) D and E
Solution: The answer is (c) A and C Explanation: Here A is Fluorine(Group 17), B is Sodium (Group 1), C is Chlorine (Group 17), D is Magnesium(Group 2) and E is Aluminium (Group 13). A and C are...
Which of the given elements A, B, C, D and E with atomic number 2, 3, 7, 10 and 30 respectively belong to the same period?
(a) A, B, C
(b) B, C, D
(c) A, D, E
(d) B, D, E
Solution: The answer is (b) B, C, D Explanation: The first period is dominated by the element with the highest atomic number, whereas the second period is dominated by elements B, C, and D.
Which of the following statements about the Modern Periodic Table is correct:
(a) It has 18 horizontal rows known as Periods
(b) It has 7 vertical columns known as Periods
(c) It has 18 vertical columns known as Groups
(d) It has 7 horizontal rows known as Groups
Solution: The answer is (c) It has 18 vertical columns known as Groups Explanation: The modern periodic table is divided into 18 groups and seven periods. Columns are referred to as groups, while...
Which of the following statement (s) about the Modern Periodic Table are incorrect
(i) The elements in the Modern Periodic Table are arranged based on their decreasing atomic number
(ii) The elements in the Modern Periodic Table are arranged based on their increasing atomic masses
(iii) Isotopes are placed in adjoining group (s) in the Periodic Table
(iv) The elements in the Modern Periodic Table are arranged based on their increasing atomic number
(a) (i) only
(b) (i), (ii) and (iii)
(c) (i), (ii) and (iv)
(d) (iv) only
Solution: Answer: (b) (i), (ii) and (iii) Explanation:...
In Mendeleev’s Periodic Table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the periodic table later
(a) Germanium
(b) Chlorine
(c) Oxygen
(d) Silicon
Solution: Answer: a) Germanium Explanation: Initially, Mendeleev designated unidentified elements as EKA- Boron, EKA- Aluminum, and EKA Silicon, which were later renamed Scandium, Gallium, and...
According to Mendeleev’s Periodic Law, the elements were arranged in the periodic table in the order of
(a) increasing atomic number
(b) decreasing atomic number
(c) increasing atomic masses
(d) decreasing atomic masses
Solution: Answer: option (c) increasing atomic masses Explanation: In accordance with Mendeleev's periodic law, the elements in the periodic table were organized in the periodic table in the order...
Up to which element, the Law of Octaves was found to be applicable
(a) Oxygen
(b) Calcium
(c) Cobalt
(d) Potassium
Solution: Answer: Option (b) Calcium Explanation: Newland's law of octaves is applicable to elements with atomic masses up to 40 da, which corresponds to the elements up to and including Calcium....
The following reaction is an example of a:
(i) displacement reaction
(ii) combination reaction
(iii) redox reaction
(iv) neutralisation reaction
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (iii) and (iv)
Answer: (c) (i) and (iii) Explanation: The reaction described here is a combination of displacement and redox reactions. The displacement reaction occurs when oxygen displaces hydrogen in ammonia,...
Which of the following is not a physical change?
(a) Boiling of water to give water vapour
(b) Melting of ice to give water
(c) Dissolution of salt in water
(d) Combustion of Liquefied Petroleum Gas (LPG)
Answer: (d) Combustion of Liquefied Petroleum Gas (LPG) Explanation: Because a new compound is generated after burning, combustion is always accompanied by a chemical change, which is irreversible...
Record the decimal developments of those normal numbers in Question 1 above which have ending decimal extensions.
Arrangements: (I) 13/3125 13/3125 = 0.00416 (ii) 17/8 17/8 = 2.125 (iii) 64/455 has a Non ending decimal development (iv)15/1600 15/1600 = 0.009375 (v) 29/343 has a Non ending decimal development...
Without really playing out the long division, state whether the accompanying normal numbers will have an ending decimal extension or a non-ending rehashing decimal development:(I) 13/3125 (ii) 17/8 (iii) 64/455 (iv) 15/1600 (v) 29/343 (vi) 23/(2352) (vii) 129/(225775) (viii) 6/15 (ix) 35/50 (x) 77/210
Solutions: Note: If the denominator has just factors of 2 and 5 or as 2m ×5n then it has ending decimal extension. On the off chance that the denominator has factors other than 2 and 5, it has a...
There is a roundabout way around a games field. Sonia requires 18 minutes to drive one round of the field, while Ravi requires 12 minutes for the equivalent. Assume the two of them start at a similar point and simultaneously, and head a similar way. After how long will they meet again at the beginning stage?
Solution: Since, Both Sonia and Ravi move a similar way and simultaneously, the technique to make when they will meet again at the beginning stage is LCM of 18 and 12. Consequently, LCM(18,12) =...
Clarify why 7 × 11 × 13 + 13 and 7 × 6 × 5 × 4 × 3 × 2 × 1 + 5 are composite numbers.
Solution: By the meaning of composite number, we know, assuming a number is composite, it implies it has factors other than 1 and itself. In this way, for the given articulation; 7 × 11 × 13 + 13...
Check whether 6n can end with the digit 0 for any regular number n.
Solution: If the number 6n closures with the digit zero (0), then, at that point it ought to be distinct by 5, as we probably are aware any number with unit place as 0 or 5 is detachable by 5. Prime...
Considering that HCF (306, 657) = 9, discover LCM (306, 657).
Solutiont: As we realize that, HCF×LCM=Product of the two given numbers Accordingly, 9 × LCM = 306 × 657 LCM = (306×657)/9 = 22338 Consequently, LCM(306,657) = 22338
Discover the LCM and HCF of the accompanying numbers by applying the great factorisation technique.
(I) 12, 15 and 21 (ii) 17, 23 and 29 (iii) 8, 9 and 25 Solution: (I) 12, 15 and 21 Composing the result of prime components for every one of the three numbers, we get, 12=2×2×3 15=5×3 21=7×3...
Discover the LCM and HCF of the accompanying sets of numbers and check that LCM × HCF = result of the two numbers.
(I) 26 and 91 (ii) 510 and 92 (iii) 336 and 54 Solution: (I) 26 and 91 Communicating 26 and 91 as result of its excellent elements, we get, 26 = 2 × 13 × 1 91 = 7 × 13 × 1 In this manner, LCM (26,...
Express each number as a result of its superb elements:
(I) 140 (ii) 156 (iii) 3825 (iv) 5005 (v) 7429 Solution (I) 140 By Taking the LCM of 140, we will get the result of its great factor. Subsequently, 140 = 2 × 2 × 5 × 7 × 1 = 22×5×7 (ii) 156 By...
Write the functions of the following a. Centromere b. Cell wall c. Smooth ER d. Golgi Apparatus e. Centrioles
A.Centromere – It holds two chromatids or sister chromatids of a chromosome. B. Cell wall -It is only present in plant cells which gives shape and protection to the cell from mechanical supports. C....
Are the different types of plastids interchangeable? If yes, give examples where they are getting converted from one type to another.
Yes, plastids are interchangeable in their form in plants . Three types of plastids –A.Chloroplasts -greenB.Chromoplasts -Red, Yellow, OrangeC. Leucoplasts -Colourless Depending upon the different...
Draw a neat and well-labelled diagram of the male reproductive system of a frog.
Frog is a poikilothermic, exhibits camouflage and undergoes aestivation and hibernation, how are all these benefits to it?
During hibernation and an aestivation, it sleeps and uses stored energy in the body and emerges after the bad environmental temperature has passed. Camouflage helps in the frog’s protection and...
Mention special features of an eye in Cockroach.
Compound eyes of cockroach that contain numerous small visual units.Ommatidia also known as visual unit in their eyeEyes have a lower resolution buthaving higher sensitivity
How do you distinguish between dorsal and ventral surface of the body of earthworm?
Dorsal surface of the body of an earthworm has a dark colour dorsal median line than the ventral surface of the body of earthworm.
Why are blood, bone and cartilage called connective tissue?
They play an important role in the binding and connection of different tissues and organs. They help in providing the structural in the form of rigidity, support and protection of the body. They...
How does a gap junction facilitate intercellular communication?
Occurs by the communication between two cells bypassing the small signaling molecules from one cytoplasm to neighbor cytoplasm.
Couplet in ordered key means ________________ .
solution: The ordered key gives a specific design based on which the client can figure out the ordered situation of the obscure species. Couplet implies a couple which is of differentiating...
What does ICZN rely on?
Arrangement: ICZN represents International Code of Zoological Nomenclature. It directs a uniform arrangement of zoological terminology.
Match the following and choose the option which is right.
I A. Family B. Kingdom C. Order D. Species E. Genus II i. tuberosum ii. Polymoniales iii. Solanum iv. Plantae v. Solanaceae Options are as follows: a. A-iv, B-iii, C-v, D-ii, E -i...
. All living organisms are linked because
a. They have the common genetic materials b. They all share a common genetic material but of varying degrees c. All have common cellular organization d. none of these Solution: Option (b) They all...