.Ans: Given is the work function $0.1 \mathrm{eV}$, $$ \phi_{o}=h v_{0} $$ Class 12 Physics $\underline{\text { wuw. vedantu.com }}$ 1 $10 a-x=10 a-2.5 a=7.5 a$ from charge $9 q$
)Ans: We are given the refractive index of glass to be, $\mu=1.5$ BreWster angle $=\theta$ Brewster angle is known to be related to refractive index as: $$ \begin{array}{l} \tan \theta=\mu \\...
west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points above the horizontal. The horizontal component of the earth’s field is measured to be 
Specify the direction and magnitude of the earth’s field at the location.At a certain location in Africa, a compass points west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points above the horizontal. The horizontal component of the earth’s field is measured to be Specify the direction and magnitude of the earth’s field at the location.Ans: In the above question it is given that: Angle of declination, $\theta=12^{\circ}$ Angle of dip, $\delta=60^{\circ}$ Horizontal component of earth's magnetic field, $B_{H}=0.16 \mathrm{G}$...
and 
carrying currents of 
and 
in the same direction are separated by a distance of 
. Estimate the force on a 
section of wire A.Ans: We are given the following: Current flowing in wire $A_{1} I_{A}=8.0 \mathrm{~A}$ Current flowing in wire $B, I_{B}=5.0 \mathrm{~A}$ Distance between the two wires, $r=4.0 \mathrm{~cm}=0.04...
wire carrying a current of 
is placed inside a solenoid perpendicular to its axis. The magnetic field inside the solenoid is given to be 
. What is the magnetic force on the wire?Ans: We are given the following: Length of the wire, $I=3 \mathrm{~cm}=0.03 \mathrm{~m}$ Current flowing in the wire, $1=10 \mathrm{~A}$. Magnetic field, $B=0.27 \mathrm{~T}$ Angle between the...
and making an angle of 
with the direction of a uniform magnetic field of 
Ans: We are given the following: Current in the wire, $I=8 \mathrm{~A}$ Magnitude of the uniform magnetic field, $B=0.15 \mathrm{~T}$ Angle between the wire and magnetic field, $\theta=30^{\circ}$...
. What is the magnitude of the field 
at a point 
from the wire?Ans: We are given the following: Current in the wire, $\mathrm{I}=35 \mathrm{~A}$ Distance of a point from the wire, $r=20 \mathrm{~cm}=0.2 \mathrm{~m}$ Magnitude of the magnetic field at this point...
-turns carrying current 
.Ans: Biot - Savart law states that the magnetic field $\mathrm{dB}$ due to a current element dI at any point would be as following: $$ \begin{array}{l} \mathrm{dB} \propto \mathrm{dl} \\ \mathrm{dB}...
. An electron moving at 
is at distance 
from the wire. Find the force acting on the electron if its velocity is directed towards the wire.Ans: We are given the current through the straight wire to be, $I=10 \mathrm{~A}$ Speed of the electron, $\mathrm{v}=10^{7} \mathrm{~m} / \mathrm{s}$ Distance of electron from the wire,...
Ans: Diamagnetic substances are the ones that are weakly repelled by a magnet. For example, gold. Ferromagnetic materials are the ones that are strongly attracted by a magnet. For example, iron.
Ans: The magnetic field at the center of the network is zero. This is because, magnetic field at the center of the loop would just equal and opposite $i . e .$, magnetic field due PQR is equal and...
Ans: A cyclotron is not suitable to accelerate electron as its mass is known to be less due to which they gain speed and step out of the dee immediately,
Ans: We know the expression for torque as, $$ \begin{array}{l} \tau=\mathrm{NIAB} \\ \Rightarrow \tau \propto \mathrm{A} \end{array} $$ Since, we know that the area of circular loops is more than...
Ans: The path of a charged particle moving along the direction of a uniform magnetic field would be a straight line path as no force would act on the particle.
Ans: Two properties of the material of the wire used for suspension of the coil in a moving coil galvanometer are: i. Non-Brittle conductor ii. Restoring Torque per unit twist should be small.
Ans: From the graph: Slope $=\frac{\mathrm{i}}{\mathrm{V}}$ It is known that, $\frac{i}{V}=\frac{1}{R}$ It means that the smaller the slope, the larger the resistance.
Ans: It is known that, $$ \begin{array}{l} H=I^{2} R t \quad\left(I=\frac{V}{R}\right) \\ \Rightarrow H=\frac{V^{2}}{R^{2}} \times R \times t \\ \Rightarrow H=\frac{V^{2}}{R} t \\ \Rightarrow H...
and 
respectively which of these is the best conductor?Ans: The resistance is directly proportional to specific resistance (resistivity), when length and area of cross-section is made constant. $R=\frac{\rho I}{A}$ Hence, silver is the best conductor as...
point change from corner to corner of a square 
when a 
charge exists at the centre of the square?Ans: Point $A \& B$ are at the same distance from the point $O$. Hence,
Ans: The electric field that is present inside a dielectric decreases when it is placed in an external electric field because of polarisation as it creates an internal electric field which is...
.Ans: Gauss's Theorem has a statement that electric flux through a closed surface enclosing a charge $q$ in vacuum is $\frac{1}{\epsilon_{0}}$ times the magnitude of the charge enclosed $\mathrm{is}...
Ans: Let us suppose a capacitor is connected to a battery and it supplies a small amount of change dq at constant potential $V$, then a small amount of work done by the battery is given by $$...
and 
are filled in between the two plates, each of area A of the parallel plate capacitor as shown in the figure. Find the net capacitance of the capacitor? Area of each plate 
Ans: In the question, the two capacitors are in parallel Net Capacitance, $C=C_{1}+C_{2}$ $$ \begin{array}{l} \mathrm{C}_{1}=\frac{\mathrm{K}_{1}...
Ans: Equidistant planes which are parallel to the $x-y$ plane are the equipotential surfaces. b) a field that uniformly increases in magnitude but remains in a constant (say, z) direction, Ans:...
electrode. The dielectric strength of the gas surrounding the electrode is 
. What is the minimum radius of the spherical shell required? (You will learn from this exercise why one cannot build an electrostatic generator using a very small shell which requires a small charge to acquire a high potential.)Ans: Given that, Potential difference is given as, $V=15 \times 10^{6} \mathrm{~V}$ Dielectric strength of the surrounding gas $=5 \times 10^{\top} \mathrm{Vm}^{-1}$ Electric field intensity is...
and 
are placed at points and 
apart. a) Identify an equipotential surface of the system.Ans: The situation is represented in the adjoining figure. An equipotential surface is the plane on which the total potential is zero everywhere. This plane is normal to line AB. The plane is...
is placed between the plates. What will be the effect on the capacitance?Ans: For air $C_{0}=\frac{A \in_{0}}{d}$ Thickness $t=\frac{d}{2}$ only when $k=\infty$ $$ \begin{array}{l} C_{0}=\frac{A \in_{0}}{d} \\ C_{\text {mat }}=\frac{A \in_{0}}{(d-t)} \end{array} $$ $$...
at right angles to a uniform electric field 
is deflected in a circular path of radius 
Prove that 
Ans: The path of the electron that is travelling with velocity $\mathrm{vm} / \mathrm{s}$ at right angle of $\bar{E}$ is of circular shape. It requires a centripetal in nature, $F=\frac{m v^{2}}{r}$...
and 
respectively. What is the electric charge inside the surface?Ans: Net flux can be given as $=\phi_{2}-\phi_{1}$ Since $\phi=\frac{q}{\epsilon_{0}}$ $$ \Rightarrow \mathrm{Q}=\left(\phi_{2}-\phi_{1}\right) \in_{0} $$ The electric charge inside the surface can...
Ans: The diagrams are given as: Equipoterhibil Surfaces 3 $\mathrm{~ ( 2 c ) r o m}$
. What will be the capacitance if the distance between the plates is reduced by half and the space between them is filled with a substance of dielectric constant 6 ?Ans: For air, capacitance can be expressed as, $C_{0}=\frac{A \in_{0}}{d}$ $$ C_{0}=8 \times p F=8 \times 10^{-12} F $$ Now $d^{\prime}=\frac{d}{2}$ and $K=6$ $$ \begin{array}{l} \Rightarrow...
Ans: Electric potential at point on the equatorial line of an electric dipole can be expressed mathematically as: $$ \begin{array}{l} V=V_{P A}+V_{P B} \\ \Rightarrow...
Ans: The introduction of dielectric in a capacitor will reduce the effective charge on plate and therefore will increase the capacitance.
Ans: The relation between capacitance, area, distance and dielectric constant is $$ C=\frac{A E_{0}}{d} \Rightarrow C \propto \frac{1}{d} $$ Hence, if distance increases, capacitance decreases....
Ans: The formula $E x \frac{1}{r^{3}}$ gives the relation between electric field and distance. $$ \therefore E \propto \frac{1}{\left(\frac{r}{2}\right)^{3}} \Rightarrow E \propto \frac{8}{r^{3}} $$...
. What distance apart should these be kept in the same medium, so that force between them becomes 
?Ans: If two point charges are $q_{1}$ and $q_{2}$ separated by distance $d$, it can be expressed as: $\mathrm{F}=\frac{\mathrm{Kq}_{1} \mathrm{q}_{2}}{\mathrm{~d}^{2}}$ Suppose if force becomes...
point change from corner to corner of a square when a charge exists at the centre of the square?Ans: Point $A \& B$ are at the same distance from the point $O$. Hence,
Ans: The electric field that is present inside a dielectric decreases when it is placed in an external electric field because of polarisation as it creates an internal electric field which is...
a) on the surface Ans: Electric field intensity on the surface of the balloon would be, $$ E=\frac{\sigma}{\varepsilon_{0}} $$ Electric potential on the surface of the balloon would be, $$ V=\frac{K...
of radius 
encloses a charge 
If there is another concentric sphere 
of radius 
and there is no additional change between and 
, then find the ratio of electric flux through 
and . 
Ans: We may recall that the expression for electric flux through a surface enclosing charge q by Gauss's law is given by, $$ \phi=\frac{q}{E_{0}} $$ Where, $\varepsilon_{0}$ is the permittivity of...
of radius encloses a charge If there is another concentric sphere of radius and there is no additional change between and , then find the ratio of electric flux through and . Ans: We may recall that the expression for electric flux through a surface enclosing charge q by Gauss's law is given by, $$ \phi=\frac{q}{E_{0}} $$ Where, $\varepsilon_{0}$ is the permittivity of...
and 
are separated by a distance of 
. Find the point on the line joining the two charges where electric field is zero.Ans: Let $p$ be the point (at $x$ distance from charge $+q$ ) on the line joining the given two charges where the electric field is zero. We know that the electric field at a point at r distance...
and charge a is released from rest in a uniform electric field of intensity E. Calculate the kinetic energy attained by this particle after moving a distance between the plates.Ans: We have the electrostatic force on a charge a in electric field E given by. $\mathrm{F}=\mathrm{q} \mathrm{E} \quad \ldots \ldots(1)$ Also, we have Newton's second law of motion given by, $$...
Ans: No. The net flux entering out through a body depends on the net charge contained in the body. If the net flux is given to be zero, then it can be inferred that the net charge inside the body is...
a) What is the net charge inside the box?Ans: It is given that: Net outward flux through surface of the box, $\phi=8.0 \times 10^{3} \mathrm{Nr}^{2} / \mathrm{C}$. For a body containing net charge a, flux is given by...
through a cube of side oriented so that its faces are parallel to the coordinate planes?Ans: It is given that all the faces of the cube are parallel to the coordinate planes. Clearly, the number of field lines entering the cube is equal to the number of field lines entering out of the...
Ans: Since unlike charges attract and like charges repel each other, the particles 1 and 2 moving towards the positively charged plate are negatively charged whereas the particle 3 that moves...
Ans: When dealing with macroscopic or large-scale charges, the charges used are huge in number as compared to the magnitude of electric charge. Hence, the quantization of electric charge is of no...
Ans: The statement 'electric charge of a body is quantized' suggests that only integral $(1,2,3,4, \ldots, \mathrm{n})$ number of electrons can be transferred from one body to another. This further...
with respect to a uniform electric field of 
experiences a torque of 
. Calculate dipole moment of the dipole?Ans: It is given that $$ \begin{array}{l} \theta=30^{\circ} \\ \tau=9 \times 10^{-26} \mathrm{Nm} \\ E=10^{4} \mathrm{~N} / \mathrm{C} \end{array} $$ Dipole moment P needs to be calculated. It is...
across the plates of two capacitors 
and versus increase of charge 
stored on them. Which of the two capacitors have higher capacitance? Give reason for your answer.Ans: It is known that $c=\frac{Q}{V}$ Clearly, for a given charge $\mathrm{Q}$. $c \propto \frac{1}{V}$ Now, from the given graph, it is seen that $\mathrm{V}_{\mathrm{A}}
Ans: Two electric lines of force can never intersect each other. Suppose if they intersect, then at the point of intersection, there can be two tangents drawn. These two tangents are supposed to...
Ans: Force on both the electron as well as the proton in the uniform field would be equal because $\mathrm{F}=\mathrm{kq}$ and it is known that charge on both electron and proton are the same. On...
Ans: Charge on a body is said to be 1 coulomb if it experiences a force of repulsion or attraction of $9 \times 10^{9} \mathrm{~N}$ from another equal charge when they are separated by a distance of...
? 
?Ans: 1.The S.I. unit of electric dipole moment is $\mathrm{Cm}$. 2. The S.I. unit of electric field intensity is N/C.
and 
?Ans: Suppose that the rod $\mathrm{P}$ is negatively charged. As it attracts rod $\mathrm{R}$, it can be said that $\mathrm{R}$ is positively charged. Also, since $P$ repels rod $Q$, it can be said...
Ans: Dielectric constant of a medium is given by $$ \begin{array}{l} k=\frac{F_{y}}{F_{M}}=\frac{\text { force between the charges in vaccum }}{\text { force between two charges in medium }} \\...
Solution 8: The following processes are involved in the extraction of zinc from zinc blende: (i) Concentration: Zinc blende ore is crushed and the concentration done by froth- floatation process....
Solution 8: The following processes are involved in the extraction of zinc from zinc blende: (i) Concentration: Zinc blende ore is crushed and the concentration done by froth- floatation process....
Solution 7: In the blast furnace reduction of iron oxides take place at different temperature ranges as shown below. At $500-800 \mathrm{~K}$ $$ \begin{array}{l} 3 \mathrm{Fe}_{2}...
Solution The common elements present in the anode mud are antimony, selenium, tellurium, silver, gold and platinum. These elements settle down under anode as anode mud because they are less reactive...
and 
which is a better reducing agent at 673K?Solution 5: This can be explained thermodynamically, taking entropy and free energy changes into account (a) $C(s)+O_{2}(g) \rightarrow C O_{2}(g)$ (b) $2...
Solution 4: (i) Zone refining: This method is used for production of semiconductors and other metals of very high purity, e.g., $\mathrm{Ge}, \mathrm{Si}, \mathrm{B}, \mathrm{Ca}$ and $\mathrm{In}$....
Solution 4: (i) Zone refining: This method is used for production of semiconductors and other metals of very high purity, e.g., $\mathrm{Ge}, \mathrm{Si}, \mathrm{B}, \mathrm{Ca}$ and $\mathrm{In}$....
Solution 3: $\Delta_{f} G^{o}$ of $\mathrm{Cu}_{2} \mathrm{~S}$ is more negative than $\Delta_{f} G^{\circ}$ of $\mathrm{CS}_{2} \mathrm{H}_{2} S$. So $C_{u} 2 S$ can not be reduced by carbon or...
Solution 2: The role of depressant is to prevent one type of sulphide ore particles from forming the froth with air bubbles. $\mathrm{NaCN}$ is used as a depressant to separate lead sulphide (PbS)...
Solution Copper can be extracted by hydrometallurgy but not zinc, this is because $E_{Z n^{2}+Z n}^{o}=-0.76 \mathrm{~V}$ lower than that of $E_{\mathrm{Cu}^{2+} / C i}^{o}=-0.34 \mathrm{~V}$ Hence,...
and 
can reduce 
? What are those conditions?Solution Yes, below $1350^{\circ} \mathrm{C}, \mathrm{Mg}$ can reduce $\mathrm{Al}_{2} \mathrm{O}_{3}$ and above $1350^{\circ} \mathrm{C}, \mathrm{Al}$ can reduce $\mathrm{MgO}$. This can be...
is thermodynamically feasible as is apparent from the Gibbs energy value. Why does it not take place at room temperature?Solution This is explained on the basis of $\mathrm{Keq}$, the equilibrium constant. In the given redox reaction, all reactants and products are solids at room temperature, so, there is no...
Solution 2: Aluminium contains silica $\left(\mathrm{SiO}_{2}\right)$, iron oxide $\left(\mathrm{Fe}_{2} \mathrm{O}_{3}\right)$ and titanium oxide $\left(\mathrm{TiO}_{4}\right)$ as impurities....
Solution Ores which are magnetic in nature can be separated from non-magnetic gangue particles by magnetic separation method. For ex: ores of iron such as haemetite $\left(\mathrm{Fe} 2...
(i) $\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)(\mathrm{CN})(\mathrm{en})_{2}\right]^{2+}$ Ans: Let us assume that the coordination number of Co is X. Therefore, we can write: $$...
Ans: These are explained below: (i) Unidentate ligand Ligands with only one donor site are called unidentate ligands. For example, $\mathrm{Cl}$ and $\mathrm{NH}_{3}$ are unidentate ligands. (ii)...
![\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)(\mathrm{CN})(\mathrm{en})_{2}\right]^{2+}](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-5830aca5c4a498a25851f5ca5b2a9534_l3.png "Rendered by QuickLaTeX.com")
Ans: Let us assume that the coordination number of Co is X. Therefore, we can write: $$ \begin{array}{l} x+0+(-1)+2(0)=+2 \\ x-1=+2 \\ x=+3 \end{array} $$ So, the coordination number of cobalt is...
Ans: These are explained below: (i) Unidentate ligand Ligands with only one donor site are called unidentate ligands. For example, $\mathrm{Cl}$ and $\mathrm{NH}_{3}$ are unidentate ligands. (ii)...
Ans: All of them are explained below: (i) Coordination entity A central metal atom or anions connected to a set number of ions or molecules known as ligands comprises a coordination entity. For...
solution mixed with 
, solution in 
molar ratio gives the test of 
ion but 
solution mixed with aqueous ammonia in 
molar ratio does not give the test of 
ion. Explain. why?Ans: Let us see the reactions happening in both the cases. $$ \begin{array}{l} \left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}+\mathrm{FeSO}_{4}+6 \mathrm{H}_{2} \mathrm{O} \rightarrow...
Ans: Werner's theory is the first theory to explain the nature of bonding in coordination compounds. The main postulates of this theory are: (i) Two types of valencies, primary and secondary...
ion, given that 
for this complex is 
.Ans: We are given the overall stability constant $\left(\beta_{s}\right)=2.1 \times 10^{13}$. The overall complex dissociation equilibrium constant is the reciprocal of the overall stability...
Ans: The formula of Tetraamminediaquacobalt (III) chloride is $$ \left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)\left(\mathrm{NH}_{3}\right)_{4}\right] \mathrm{Cl}_{3} $$ (ii) Potassium...
, that would be the molality and mole fraction of each component in the solution? If the density of solution is 
then what shall be the molarity of theSolution 10 percent $w / w$ solution of glucose in water means $10 g$ glucose and $90 \mathrm{~g}$ of water. $10 \mathrm{~g}$ of glucose $=\frac{10}{180}=0.0555$ moles And $90 \mathrm{~g}$ of...
given Volume ofsolution $-\frac{\text { mass }}{\text { density }}=\frac{100}{1.504}=66.5 \mathrm{~mL}$ Molarity of solution $$ \begin{array}{l} =\frac{\text { moles of sloution } \times 1000}{\text { Volume of...
nitric acid by mass in aqueous solution. What should be the molarity of such a sample of the acid if the density of the solution is 
?Solution 4: $68 \%$ nitric acid by mass means that $68 \mathrm{~g}$ mass of nitric acid is dissolved in $100 \mathrm{~g}$ mass the solution. Molar mass of $\mathrm{HNO}_{3}=63 \mathrm{~g}...
Solution 3: (i) Mole Fraction: It is defined as the ratio of the number of moles of the solute to the total number of moles in the solution. If $\mathrm{A}$ is the number of moles of solute...
Solution Solution of hydrogen in palladium and dissolved gases in minerals
of polymer of molar mass 185,000 in 
of water at 
.Solution $$ \begin{array}{l} \text { Given } \mathrm{V}=450 \mathrm{~mL}=0.45 \mathrm{~L} \\ =37^{\circ} \mathrm{C}=310 \mathrm{~K} \\ \mathrm{R}=8.314 \mathrm{kPaL} \mathrm{k}^{-1}...
is 
. How much sucrose is to be added to 
of water such that it boils at 
.Solution Given $\Delta \mathrm{Tb}=100-99.63=3.37^{\circ}$ Mass of water w1 $=500 \mathrm{~g}$ Molar mass of water, $\mathrm{M}_{1}=18 \mathrm{~g} \mathrm{~mol}^{-1}$ Molar mass of sucrose,...
Ans: By knowing the density of an unknown metal and the dimension of its unit cell, the atomic mass of the metal can be determined. Let 'a' be the edge length of a unit cell of a crystal, 'd' be the...
Ans: The number of nearest neighbors of any constituent particle present in the crystal lattice is called its coordination number.
(i) Hexagonal close-packing and cubic close-packing? Ans: A 2-d hexagonal close-packing contains two types of triangular voids (a and b) as shown in figure 1. Let us call this 2-D structure as layer...
Ans: Higher the melting point, greater are the intermolecular forces of attraction between the atoms of a molecule and greater is the stability of that molecule. A substance with higher melting...
. Calculate the atomic radius of niobium using its atomic mass 
.Ans: It is given that the density of niobium, $\mathrm{d}=8.55 \mathrm{gcm}^{-3}$ Atomic mass, $M=93 \mathrm{gmol}^{-1}$ As the lattice is bcc type, the number of atoms per unit cell, $z=2$ Let the...
and 
Atoms of are at the corners of the cube and at the body-centre. What is the formula of the compound? What are the coordination numbers of and 
Ans: It is given that the atoms of $\mathrm{Q}$ are present at the corners of the cube. Therefore, number of atoms of $Q$ in one unit cell $=8 \times(1 / 8)=1$ It is also given that the atoms of...
and density is 
, calculate the atomic mass of silver.Ans: It is given that the edge length, $\mathrm{a}=4.07 \times 10^{-8} \mathrm{~cm}$ and density is $\mathrm{d}=$ $10.5 \mathrm{~g} \mathrm{~cm}^{3}$ As the lattice is foc type, the number of atoms...
Correct option is (i)
Electric potential at a place in an electric field is the amount of effort done to bring the unit positive charge from infinity to that point, whereas electric potential energy is the energy...
Ans: Higher the melting point, greater are the intermolecular forces of attraction between the atoms of a molecule and greater is the stability of that molecule. A substance with higher melting...
. Calculate the atomic radius of niobium using its atomic mass .Ans: It is given that the density of niobium, $\mathrm{d}=8.55 \mathrm{gcm}^{-3}$ Atomic mass, $M=93 \mathrm{gmol}^{-1}$ As the lattice is bcc type, the number of atoms per unit cell, $z=2$ Let the...
and Atoms of are at the corners of the cube and at the body-centre. What is the formula of the compound? What are the coordination numbers of and Ans: It is given that the atoms of $\mathrm{Q}$ are present at the corners of the cube. Therefore, number of atoms of $Q$ in one unit cell $=8 \times(1 / 8)=1$ It is also given that the atoms of...
. Calculate the atomic radius of niobium using its atomic mass .Ans: It is given that the density of niobium, $\mathrm{d}=8.55 \mathrm{gcm}^{-3}$ Atomic mass, $M=93 \mathrm{gmol}^{-1}$ As the lattice is bcc type, the number of atoms per unit cell, $z=2$
B 
C 
D None of theseCorrect option is (A) $10^{\circ}$ $\frac{\mathrm{F}_{\mathrm{e}}}{\mathrm{F}_{\mathrm{p}}}=10^{0}=1$, because force depends only on charges, distance and nature of medium and not type of charge. As...
and Atoms of are at the corners of the cube and at the body-centre. What is the formula of the compound? What are the coordination numbers of and Ans: It is given that the atoms of $\mathrm{Q}$ are present at the corners of the cube. Therefore, number of atoms of $Q$ in one unit cell $=8 \times(1 / 8)=1$ It is also given that the atoms of...
and Atoms of are at the corners of the cube and at the body-centre. What is the formula of the compound? What are the coordination numbers of and Ans: It is given that the atoms of $\mathrm{Q}$ are present at the corners of the cube. Therefore, number of atoms of $Q$ in one unit cell $=8 \times(1 / 8)=1$ It is also given that the atoms of...
and carrying charge are separated by some distance. If they are in equilibrium under mutual gravitational and electrostatic forces, then 
(in 
) is of the order of: 
Correct option is (B) $10^{-10}$ Given : Gravitational force $=$ Electrostatics force Let the distance between the rwo charges be r. $$ \begin{array}{l} \Rightarrow \frac{\mathrm{G}(\mathrm{m})...
In electrostatic force, the force of medium depends on charges while the force of the medium due to gravity does not depend on masses. There is no concept of induced mass.
and density is , calculate the atomic mass of silver.Ans: It is given that the edge length, $\mathrm{a}=4.07 \times 10^{-8} \mathrm{~cm}$ and density is $\mathrm{d}=$ $10.5 \mathrm{~g} \mathrm{~cm}^{3}$ As the lattice is foc type, the number of atoms...
Correct option is (D) Dependence on the intervening medium In electrostatic force, the force of the medium depends on charges while the force of the medium due to gravity does not depend on masses....
is : Correct option is (C) 625 We need force of repulsion $=10^{-19} \mathrm{~N}$ Let $n$ no. of increase electrons be placed on each sphere $$ \begin{array}{l} \Rightarrow...
. Show that the calculated density is in agreement with its measured value of 
Ans: Edge length, $a=3.61 \times 10^{-6} \mathrm{~cm}$ As the lattice is fcc type, the number of atoms per unit cell, $z=4$ Atomic mass, $\mathrm{M}=63.5 \mathrm{~g} \mathrm{~mol}^{-1}$ We also know...
Correct option is(c) same Since the magnitude of the charge of electron and proton is the same, e, the electrostatic force between two protons is the same compared to the electrostatic force between...
Ans: Semiconductors are substances having conductance in the intermediate range $10^{-6}$ to $10^{4}$ ohm $^{-1} \mathrm{~m}^{-1}$. The two main types of semiconductors are: (i) n-type semiconductor...
-type or an 
-type semiconductor.(i) Ge doped with In Ans: Ge (a group 14 element) is doped with In (a group 13 element). Therefore, a hole will be created and the semiconductor generated will be a p-type semiconductor. (ii) B...
Ans: Let the number of oxide $\left(\mathrm{O}^{2-}\right)$ ions be $\mathrm{x}$. So, number of octahedral voids $=x$ It is given that two out of every three octahedral holes are occupied by ferric...
is doped with 
of 
, what is the concentration of cation vacancies?Ans: It is given that $\mathrm{NaCl}$ is doped with $10^{3} \mathrm{~mol} \%$ of $\mathrm{SrCl}_{2}$. This means that $100 \mathrm{~mol}$ of $\mathrm{NaCl}$ is doped with $10^{3} \mathrm{~mol}$ of...
Correct option is D current leads ahead of the emf $\mathrm{D}$ In circuits with primary capacitive loads, currently leads to the voltage. This is because the current must flow first to the two...
Correct option is A $\mathrm{W}=\frac{\varepsilon_{0} \mathrm{~A} \mathrm{~V} \mathrm{~h}^{2}}{2 \mathrm{~d}}(1-1 / \mathrm{k})$ C $Q=\frac{\varepsilon_{0} A V}{d}$ D $\quad E=\frac{V}{k d}$ As...
.(i) What is the length of the side of the unit cell? Ans: For cubic close-packed structure: $$ \begin{array}{l} \mathrm{a}=2 \sqrt{2} \mathrm{r} \\ \Rightarrow 2 \sqrt{2}=125 \mathrm{pm} \\ =353.55...
and 
, then 
is: 
Correct option is B $\frac{2}{3}$ Let the charge stored by a capacitor with dielectric constant 3 be $Q$. Thus energy stored be $\frac{\mathrm{Q}^{2}}{2 \mathrm{C}_{1}}$ Since the charge remains the...
The correct option is (A) charge Q When the capacitor is kept at a voltage, it gains charge. Now when the system is isolated, the charge present on the capacitor cannot change because of the law of...
is doped with of , what is the concentration of cation vacancies?Ans: It is given that $\mathrm{NaCl}$ is doped with $10^{3} \mathrm{~mol} \%$ of $\mathrm{SrCl}_{2}$. This means that $100 \mathrm{~mol}$ of $\mathrm{NaCl}$ is doped with $10^{3} \mathrm{~mol}$ of...
$\mathrm{~ O ~ W e i s c o d i s ~ T o p}$ Correct option is B increases As the dielectric slab is introduced there is some charge distribution in the slab and because of this, the electric field...
.(i) What is the length of the side of the unit cell? Ans: For cubic close-packed structure: $$ \begin{array}{l} \mathrm{a}=2 \sqrt{2} \mathrm{r} \\ \Rightarrow 2 \sqrt{2}=125 \mathrm{pm} \\ =353.55...
Ans: As isotropic solid has the same value of physical properties when measured along different directions. Therefore, the given solid, having the same value of refractive index along all...
The correct option is B decreases finitely Quality factor $Q$ is given by: $$ \mathrm{Q}=\frac{\omega_{0} \mathrm{~L}}{\mathrm{R}} $$ Thus, as $\mathrm{R}$ increases Q definitely decreases.
Transformer works on. 
and DC The correct option is A AC only Transformer works on the principle of Electromagnetic induction i.e an emf is induced in the coil if the magnetic flux linked with the coil changes. Magnetic flux in...
Correct option is B $\frac{\mathrm{Q}^{2}}{2 \mathrm{\varepsilon}_{0} \mathrm{~A}}$ The magnitude of electric field by any one plate is $\mathrm{E}=\frac{\sigma}{2...
Ans: Similar to liquids, glass has a tendency to flow, though very slowly. Therefore, glass is considered as a super cooled liquid. This is the reason that glass windows and doors are slightly...
Correct option is D $\frac{\mathrm{f}_{0}}{\mathrm{f}_{2}-\mathrm{f}_{1}}$ Quality factor is a relation between stored energy and energy dissipation in a device or system. As per definition of...
Q-factor: In LCR Circuit, the ratio of resonance frequency to the difference of its neighboring frequencies so that their corresponding current is $1 / \sqrt{2}$ times of the peak value, is called...
Ans: The intermolecular forces of attraction that are present in solids are very strong, The constituent particles of solids have fixed positions i.e., they are rigid. Hence, solids have a definite...
Ans: The intermolecular forces of attraction that are present in solids are very strong. The constituent particles of solids cannot move from their positions i.e., they have fixed positions....
Biot savart law is the base of all magnetism and the effects of current. It states that the magnetic field intensity due to an element of a current-carrying wire at a point near the element is...
The correct option is A Mutual induction Mutual inductance is where the magnetic field generated by a coil of wire induces a voltage in an adjacent coil of wire. A transformer is a device...
Ans: The given properties are the properties of a covalent or network solid. Therefore, the given solid is a covalent or network solid. Examples of such solids include diamond ( $\mathrm{C}$ ) and...
. supplyThe correct option is D) A device for stepping up or down the voltage of $A C$. supply A transformer is a device that is used to either raise or lower voltages and currents in an electrical circuit....
Ans: Potassium sulphate $\rightarrow$ ionic solid Tin Metallic $\rightarrow$ solid Benzene $\rightarrow$ Molecular (non-polar) solid Urea $\rightarrow$ Polar molecular solid Ammonia $\rightarrow$...
For the construction of the transformer, you must have two coils having mutual inductance and a laminated steel core. The two coils are insulated from each other and from the steel core. The device...
Principle: The transformer is based on the principle of electromagnetic induction. The phenomenon of producing an induced emf due to the changes in the magnetic flux associated with a closed circuit...
(i) Hexagonal and monoclinic unit cells Ans: Hexagonal unit cell: For a hexagonal unit cell $$ \begin{array}{l} a=b \neq c \\ \text { and } \alpha=\beta= \\ y=120^{\circ} \end{array} $$ Monoclinic...
Ans: The six parameters that characterize a unit cell are as follows. (i) Its dimensions along the three edges, $a, b$, and $c$. These edges may or may not be equal. (ii) Angles between the edges....
Ans: The significance of a lattice point is that each lattice point represents one constituent particle of a solid which may be an atom, a molecule (group of atom), or an ion.
and 
. The element forms ccp and atoms of M occupy 
of tetrahedral voids. What is the formula of the compound?Ans: The ccp lattice is formed by the atoms of the element $\mathrm{N}$. Here, the number of tetrahedral voids generated is equal to twice the number of atoms of the element $\mathrm{N}$. According...
Correct option is c $\frac{1}{2 \pi} \sqrt{\frac{1}{L C}-\frac{R^{2}}{L^{2}}}$ Megritude of admittanos $Y=\frac{1}{Z}$ is given by: $$ |\mathrm{Y}|=\frac{\mid \mathrm{H}^{2}...
of it? How many of these are tetrahedral voids?A compound is formed by two elements $\mathrm{M}$ and $\mathrm{N}$. The element $\mathrm{N}$ forms ccp and atoms of M occupy $1 / 3 r d$ of tetrahedral voids. What is the formula of the compound?
radian 
radian 
radian The correct option is D zero We know that phase difference is given by: $$ \phi=\arctan \left(\frac{\left(\mathrm{X}_{\mathrm{L}}-\mathrm{X}_{\mathrm{C}}\right)}{\mathrm{R}}\right) $$ at resonance...
Correct option is c $\frac{1}{2 \pi} \sqrt{\frac{1}{L C}-\frac{R^{2}}{L^{2}}}$ Megritude of admittanos $Y=\frac{1}{Z}$ is given by: $$ |\mathrm{Y}|=\frac{\mid \mathrm{H}^{2}...
Correct option is a $\frac{1}{2 \pi \sqrt{L C}}$ For rescnance $$ \mathrm{X}_{\mathrm{L}}=\mathrm{X}_{\mathrm{E}} $$ $$ \begin{aligned} \mathrm{kL} &=\frac{1}{\mathrm{wC}} \\ \mathrm{w}...
Ans: In a square close-packed layer, the molecule is in contact with four of its neighbours, Therefore, the two-dimensional coordination number of a molecule in a square close packed layer is $4 .$
The correct option is A Terrestrial Magnetism
The correct option is C inductance is very high and resistance is negligible. The power consumption in an AC circuit is zero when the circuit contains only inductance or capacitance since the...
Ans: (i) An atom located at the corner of a cubic unit cell is shared by eight adjacent unit cells. Therefore, 1 / 8 th portion of the atom is shared by one unit cell. (ii) An atom located at the...
(i) $\mathrm{ZnS}$, Ans: ZnS shows Frenkel defect. (ii) $\mathrm{AgBr}$ Ans: AgBr shows Frenkel defect as well as Schottky defect.
The correct option is (A) 0 Since reactive impedance at resonance is zero and we know that, $\tan \phi=\frac{X_{L}-X_{C}}{Z}$ but $\mathrm{X}_{\mathrm{L}}-\mathrm{X}_{\mathrm{C}}=0$ therefore...
Ans: When a solid is heated, vacancy defects can arise. A solid crystal is said to have vacancy defects when some of the lattice sites are vacant. Vacancy defect leads to a decrease in the density...
forms a cubic unit cell with an edge length 
. If its density is 
what is the nature of the cubic unit cell?Ans: It is given that density of the element, $d=2.7 \times 10^{3} \mathrm{~kg} \mathrm{~m}^{-3}$ Molar mass, $M=2.7 \times 10^{-2} \mathrm{~kg} \mathrm{~mol}^{-1}$ Edge length, $\mathrm{a}=405...
Ans: Ferromagnetic substances would make better permanent magnets. In solid state, the metal ions of ferromagnetic substances are grouped together into small regions. These regions are called...
Ans: An n-type semiconductor conducts because of the presence of extra electrons. Therefore a group 14 element can be converted to n-type semiconductor by doping it with a group 15 element.
Ans: The colour develops because of the presence of electrons in the anionic sites. These electrons absorb energy from the visible part of radiation and get excited. For example, when crystals of...
Ans: When a cation of higher valence is added to an ionic solid as an impurity to it, the cation of higher valence replaces more than one cation of lower valence so as to keep the crystal...
i. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}+\mathrm{HCl} \rightarrow$ Ans: n-propylammonium chloride ii. $\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{3}...
Solution 9: \begin{tabular}{l} \hline $\mathrm{P} \square=23.8 \mathrm{~mm} \mathrm{Hg}$ \\ $\mathrm{W} 2=50 \mathrm{~g}, \mathrm{M}_{2}($ urea $)=60 \mathrm{~g} \mathrm{~mol}^{-1}$ \\ $\mathrm{w}...
in water is 
at 
. Calculate the quantity of in 
of soda water when packed under 
pressure at .Solution 7: $$ \mathrm{KH}=1.67 \times 10_{8} \mathrm{~Pa} $$ $$ \begin{array}{l} \hline P_{A}^{o}=450 \mathrm{~mm}, P_{B}^{o}=700 \mathrm{~mm}, P_{\text {total }}=600 \mathrm{~mm} \\ \text { As...
![\mathrm{K}_{5}\left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-32cbfc6fdf62516d53f060567ba2033d_l3.png "Rendered by QuickLaTeX.com")
Ans: The complex will be $\left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{8}\right]^{3}$. Oxidation state of cobalt will be $=x-6=-3$ The oxidation state is $=+3$ Coordination number...
Ans: The carbon metal linkages in metal carbonyls are characterized by both s and p. M-Ca bond consists of a donation into an empty metal orbital of a lone pair of electrons on the carbonyl carbon....
Ans: In $\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3 v}$ the oxidation state of $\mathrm{Cr}$ is in $+3$ oxidation state, which will cause the configuration of $\mathrm{Cr}$ as...
(i) $\quad\left[\mathrm{CO}\left(\mathrm{NH}_{3}\right)_{6}\right] \mathrm{Cl}_{3}$ Ans: The IUPAC name of the compound is Hexaamminecobalt(III) chloride. (ii)...
of 
molal aqueous solution.Solution 4: $0.25$ molal aqueous solution to urea means that Moles of urea $=0.25$ mole Mass of solvent $(\mathrm{NH} 2 \mathrm{CONH} 2)=60 \mathrm{~g} \mathrm{~mol}^{-1}$ $\therefore 0.25$ mole of...
of 
in 
ofsolution (b) $30 \mathrm{~mL}$ of $0.5 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ diluted to $500 \mathrm{~mL}$. Solution 3: (a) Molar mass of $\mathrm{Co}\left(\mathrm{NO}_{3}\right)_{2}, 6...
by mass in carbon tetrachloride.Solution 2: $30 \%$ by mass of $\mathrm{C} 6 \mathrm{H} 6$ in $\mathrm{CCl} 4 \Rightarrow 30 \mathrm{~g} \mathrm{C} 6 \mathrm{H} 6$ in $100 \mathrm{~g}$ solution $\therefore$ Number of moles of...
and carbon tetrachloride 
if 
of benzene is dissolved in 
of carbon tetrachloride.Solution Mass percentage of $$ \begin{array}{l} C_{6} H_{6}=\frac{\text { Mass of } \mathrm{C}_{6} \mathrm{H}_{6}}{\text { Total mass of the solution }} \times 100 \% \\ =\frac{\text { Mass of }...
(i) Tetra phosphorus decoxide $\left(\mathrm{P}_{4} \mathrm{O}_{20}\right)$ (ii)Ammonium phosphate $\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}$ (iii) $\mathrm{SiC}$ (iv) $\mathrm{I}_{2}$ (v)...
Ans: The arrangement of the constituent particles makes glass different from quartz. In glass, the constituent particles have short range order, but in quartz, the constituent particles have both...
Ans: Amorphous solids are the solids that have their constituent particles of irregular shape and have short range order. These solids are isotropic in nature and melt over a range of temperature....
Solution Soaps work in soft water. However, they are not effective in hard water. In contrast, synthetic detergents work both in soft water and hard water. Therefore, synthetic detergents are better...
Solution Alitame is a high potency sweetener. It is difficult to control the sweetness of food while using alitame as an artificial sweetener.
Solution Artificial sweetening agents such as saceharin, alitame, and aspartame can be used in preparing sweets for diabetie paticats. Question 19: What problem arises in using alitame as artificial...
Solution Artificial sweetening agents are chemicals that sweeten food. However, unlike natural sweeteners, they do not add calories to our body. They do not harm the human body. Some artificial...
Solution Aspartame becomes unstable at cooking temperature. This is the reason why its use is limited to cold foods and drinks.
Solution Food preservatives are chemicals that prevent food from spoilage due to microbial growth. Table salt, sugar, vegetable oil, sodium benzoate (ChHsCOONa), and salts of propanoic acid are...
Solution Tincture of iodine is a $2-3$ percent solution of wodine in alcohol - water mixture, It is applied to wounds as an antiseptic.
Solution The main constituents of dettol are chloroxylenol and a-terpineol. CC1=CC(O)=CC(C)C1Cl CC1=CCC(C(C)(C)Br)CC1 Chatisiars a-ticyanat
Solution Phenol can be used as an antiseptic as well as a disinfectant. $0.2$ peroent solution of phenol is used as an antiseptic, while 1 per cent of its solution is used as a disinfectant.
Solution Cimetidine and rantidine are better antacids as they control the root eause of acidity. These drugs prevent the interaction of histamine with the receptors present in the stomach walls....
Solution Antiseptics and disinfectants are effective against micro-organisms. However, antiseptics are applied to the living tisswes such as wounds, cuts, ulcers, and diseased skin surfaces, while...
Solution 9: Antibiotics that are effective against a wide range of gram-positive and gram-negative bacteria are known as broad spectrum antibiotics. Chloramphenicol is a broud spectrum antibiotic....
Solution \&: Anti-depressant drugs are needed to counteract the effect of depression. These drugs inhibit Enzymes catalysing the degradation of the neurotransmitter, noradrenaline. As a result, the...
Solution Specific drugs affect particular receptors. Antacids and anti-allergie drugs work on different receptors. This is the reason why antacids and anti-allergic drugs do not interfere with each...
Solution Either of the following forces can be involved in holding drugs to the active sites of enzymes, (i) Ionic bonding (ii) Hydrogen bonding (iii) Dipole - dipole interaction (iv) van der Waals...
Solution The use of chemicals for therapeutic effect is called chemotherapy. For example: the use of chemicals in the diagnosis, prevention, and treatment of diseases
Solution The macromolecules chosen as drug targets are carbohydrates, lipids, proteins, and nucleic acids,
Solution In medicinal chemistry, drug targets refer to the key molecules involved in certain metabolic pathways that result in specific diseases, Carbohydrates, proteins, lipids, and nucleic acids...
Solution The classification of drugs and the reasons for classification are as follows: (i) On the basis of pharmacological effect: This classification provides doctors the whole range of drugs...
i. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}+\mathrm{HCl} \rightarrow$ Ans: n-propylammonium chloride ii. $\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{3}...
Ans: Considering the inductive effect of alkyl groups $\mathrm{NH}_{3}, \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NH}_{2}$ and $\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{NH}$ can be...
forms 2,4 -DNP derivative, reduces Tollens’ reagent and undergoes Cannizzaro reaction. On vigorous oxidation, it gives 1,2 -benzenedicarboxylic acid. Identify the compound.Ans: It is because the chemical $\left(\mathrm{C}_{9} \mathrm{H}_{10} \mathrm{O}\right)$ generates a derivative of 2,4 -dnp and reduces the reagent of Tollen. The chemical must thus be an aldehyde....
$\mathrm{H}_{3} \mathrm{C} \longrightarrow{\mathrm{C}}_{2}^{\mathrm{H}_{2}} \mathrm{CHO}+\mathrm{H}_{3} \mathrm{C} \longrightarrow \stackrel{\mathrm{H}_{2}}{\mathrm{C}}-\mathrm{CHO} \longrightarrow...
(i) $\mathrm{CH}_{3} \mathrm{CO}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CH}_{3}$ Ans: The IUPAC name of the given compound is Heptan-2-one and its common name is Methyl n-pentyl ketone. (ii)...
(i) 3-Methylbutanal Ans: The structure of 3-Methylbutanal is given below: CC(C)CC=O (ii) p-Nitropropiophenone Ans: The structure of p-Nitropropiophenone is given below: (viii) Hex-2-en-4-ynoic acid...
Ans: The IUPAC name of the given compound is 4-Methylpentanal, (ii) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COCH}\left(\mathrm{C}_{2} \mathrm{H}_{5}\right) \mathrm{CH}_{2} \mathrm{CH}_{2}...
to 109
Solution 5: Functional groups present in the molecule are: Hy trophobic part (i) Ether, and (ii) primary alcoholic group wime yodansu cion 10 "odididu Lice onun: r.toning $\mathrm{R}-\mathrm{C}=$...