NCERT Exemplar

Which of the accompanying assertions are right? (a) Cationic cleansers have germicidal properties. (b) Bacteria can corrupt the cleansers containing profoundly spread chains. (c) Some engineered cleansers can give froth even in super cold water. (d) Synthetic cleansers are not cleansers.

Solution: (a, c, d) (a) Cationic cleansers are quaternary ammonium salts of amines with acetic acid derivations, chlorides or bromides as anions. These cleansers have germicidal properties. (b)...

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Which of coming up next are anionic cleansers? (a) Sodium salts of sulphonated long chain liquor. (b) Ester of stearic corrosive and polyethylene glycol. (c) Quaternary ammonium salt of amine with acetic acid derivation particle. (d) Sodium salts of sulphonated long chain hydrocarbons.

Solution: (a, d) Sodium salts of sulphonated long chain liquor and sodium salts of sulphonated long chain hydrocarbons are anionic cleansers e.g., Sodium laurylsulphate CH3(CH2)10CH2OSO3–Na+ and...

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Which of the accompanying assertions are inaccurate with regards to penicillin? (a) An antibacterial organism. (b) Ampicillin is its engineered adjustment. (c) It has bacteriostatic impact. (d) It is a wide range anti-infection.

Solution: (c, d) Penicillin annihilates microbes by obliterating the cell mass of the microorganism or kill the microscopic organisms along these lines, it has bacteriocidal impact. Penicillin has a...

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Which of the accompanying assertions are erroneous with regards to receptor proteins? (a) Majority of receptor proteins are installed in the cell layers. (b) The dynamic site of receptor proteins opens within locale of the cell. (c) Chemical couriers are gotten at the limiting locales of receptor proteins. (d) Shape of receptor doesn’t change during connection of courier.

Solution: (b, d) Receptor proteins are implanted in the cell film and their dynamic destinations project outside area of the cell layer. State of the receptor changes during the connection of...

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Which of the accompanying assertion isn’t correct with regards to chemical inhibitors? (a) Inhibit the synergist movement of the chemical. (b) Prevent the limiting of substrate. (c) Generally, a solid covalent bond is shaped between an inhibitor and a compound. (d) Inhibitors can be cutthroat or non-serious.

Solution: (c) Inhibitors are synthetic substances which will in general lessen the action of a specific chemical. For the most part, a powerless bond, for example, H-holding, van der Waals...

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p1 and p2 are points on either of the two lines y-√3 and |x|=2 at a distance of 5units from their point of intersection.Find the coordinates of the foot of perpendicular drawn from p1 and p2 on the bisector of theangle between the given lines.

  Since, \[y\text{ }-\text{ }\surd 3\left| x \right|\text{ }=\text{ }2\]If x ≥ 0, then \[y\text{ }-\text{ }\surd 3x\text{ }=\text{ }2\text{ }\ldots ..\text{ }\left( i \right)\] If x < 0,...

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Which of the accompanying assertion is right? (a) Some sedatives work by hindering the compounds which catalyze the debasement of noradrenaline. (b) Tranquilizers are opiate drugs. (c) Tranquilizers are substance intensifies that don’t influence the message move from nerve to receptor. (d) Tranquilizers are substance intensifies that can calm torment and fever.

Solution: (a) Tranquilizers are neurologically dynamic medications. A few sedatives are antidepressants and the capacities by hindering the proteins which catalyze the corruption of noradrenaline....

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Which proclamation about ibuprofen isn’t correct? (a) Aspirin has a place with opiate analgesics. (b) It is powerful in diminishing torment. (c) It has antiblood thickening activity. (d) It is a neurologically dynamic medication.

Solution: (a) Aspirin restrains the combination of mixtures known as prostaglandins which invigorate irritation in the tissues and cause torment. Thus, it is viable in easing torment. Ibuprofen has...

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Which is the right assertion about anti-conception medication pills? (a) Contain estrogen as it were (b) Contain progesterone as it were (c) Contain a combination of estrogen and progesterone subsidiaries (d) Progesterone upgrades ovulation

Solution: (c) Birth control pills contain a combination of estrogen and progesterone subsidiaries. Both of these are sex chemicals. Progesterone stifles ovulation and estrogen control the feminine...

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Which of the accompanying assertion isn’t right? (a) Some germ-killers can be added to cleansers. (b) Dilute arrangements of certain sanitizers can be utilized as germ-free. (c) Disinfectants are antimicrobial medications. (d) Antiseptic prescriptions can be ingested.

Solution: (d) Antiseptics are applied to the living tissues like injuries, cuts and unhealthy skin surfaces. Disinfectant prescriptions, for example, anti-microbials can't be ingested.  

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Find the number of integers greater than 7000 that can be formed with the digits 3, 5, 7, 8 and 9 where no digits are repeated. [Hint: Besides 4-digit integers greater than 7000, five digit integers are always greater than 7000.]

Solution: As per the question, The digits that can be used $=3,5,7,8,9$ As, no digits can be repeated, No. of integers is ${ }^{5} \mathrm{P}_{5}=5 !=120$ For a 4 digit integer to be greater than...

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There are 10 persons named P1,P2,P3, … P10. Out of 10 persons, 5 persons are to be arranged in a line such that in each arrangement P1 must occur whereas P4 and P5 do not occur. Find the number of such possible arrangements. [Hint: Required number of arrangement =7C4× 5!]

Solution: It is known that $\begin{array}{l} { }^{\mathrm{n}} \mathrm{C}_{\mathrm{r}} \\ =\frac{\mathrm{n} !}{\mathrm{r} !(\mathrm{n}-\mathrm{r}) !} \end{array}$ As per the question, There are a...

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A kite is moving horizontally at a height of 151.5 meters. If the speed of kite is 10 m/s, how fast is the string being let out; when the kite is 250 m away from the boy who is flying the kite? The height of boy is 1.5 m.

Speed of the kite(V) \[=\text{ }10\text{ }m/s\] Leave FD alone the tallness of the kite and AB be the stature of the kite and AB be the tallness of the kid. Presently, let AF \[=\text{ }x\text{ }m\]...

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A candidate is required to answer 7 questions out of 12 questions, which are divided into two groups, each containing 6 questions. He is not permitted to attempt more than 5 questions from either group. Find the number of different ways of doing questions.

Solution: It is known that, $\begin{array}{l} { }^{n} C_{r} \\ =\frac{n !}{r !(n-r) !} \end{array}$ 6 = Number of questions in group A 6 = Number of questions in group B As per the question, The...

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Eight chairs are numbered 1 to 8. Two women and 3 men wish to occupy one chair each. First the women choose the chairs from amongst the chairs 1 to 4 and then men select from the remaining chairs. Find the total number of possible arrangements.

Solution: It is known that, ${ }^{n} P_{r}$ $=\frac{\mathrm{n} !}{(\mathrm{n}-\mathrm{r}) !}$ As per the question, In 4 different way $W_{1}$ can occupy chairs marked 1 to 4. $$...

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The inverse square law in electrostatics is |F|=\frac{e^{2}}{\left(4 \pi \epsilon_{0}\right)} r^{2} for the force between an electron and a proton. The 1 \mathrm{r} dependence of |\mathbf{F}| can be understood in quantum theory as being due to the fact that the ‘particle’ of light (photon) is massless. If photons had a mass \mathrm{mp}, force would be modified to |F|=\frac{e^{2}}{\left(4 \pi \epsilon_{0}\right)} r^{2}\left[\frac{1}{r^{2}}+\frac{\lambda}{r}\right] \quad where \lambda=\mathrm{m} \mathrm{cp} / \hbar and h=\hbar / 2 \pi . Estimate the change in the ground state energy of an H-atom if \mathrm{mp} were 10^{-6} times the mass of an electron.

$m_{\mathrm{p}} c^{2}=10^{-6} \times$ electron mass $\times c^{2}$ $=10^{-6} \times 0.5 \mathrm{MeV}$ $\approx 10^{-6} \times 0.5 \times 1.6 \times 10^{-13}$ $\approx \mathrm{O} .8 \times 1...

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Consider aiming a beam of free electrons towards free protons. When they scatter, an electron and a proton cannot combine to produce an H-atom,
(a) because of energy conservation
(b) without simultaneously releasing energy in the form of radiation
(c) because of momentum conservation
(d) because of angular momentum conservation

The correct options are: (a) because of energy conservation (b) without simultaneously releasing energy in the form of radiation

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An ionised H-molecule consists of an electron and two protons. The protons are separated by a small distance of the order of angstrom. In the ground state,
(a) the electron would not move in circular orbits
(b) the energy would be (2) 4 times that of an \mathrm{H}-atom
(c) the electrons, the orbit would go around the protons
(d) the molecule will soon decay in a proton and an \mathrm{H}-atom

The correct options are: (a) the electron would not move in circular orbits (c) the electrons, the orbit would go around the protons

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The binding energy of an H-atom, considering an electron moving around a fixed nucleus (proton), is B=\frac{m e^{4}}{8 n^{2} \epsilon_{0}^{2} h^{2}} \quad(\mathrm{~m}= electron mass ) . If one decides to work in a frame of reference where the electron is at rest, the proton would be moving around it. By similar arguments, the binding energy would be B=\frac{M e^{4}}{8 n^{2} \epsilon_{0}^{2} h^{2}} \quad (M = proton mass) This last expression is not correct because
(a) n would not be integral
(b) Bohr-quantisation applies only to electron
(c) the frame in which the electron is at rest is not inertial
(d) the motion of the proton would not be in circular orbits, even approximately

The correct option is: (c) the frame in which the electron is at rest is not inertial

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Nuclei with magic no. of proton Z=2,8,20,28,50,52 and magic no. of neutrons N=2,8,20,28,50,82 and 126 are found to be very stable
(i) Verify this by calculating the proton separation energy Sp for \operatorname Sn^ {120}(\mathrm{Z}=50) and \mathrm Sb^ {121}=(\mathrm{Z}=51). The proton separation energy for a nuclide is the minimum energy required to separate the least tightly bound proton from a nucleus of that nuclide. It is given by \mathrm{Sp}=\left(\mathrm{M}_{\mathrm{z}-1}, \mathrm{~N}+\mathrm{M}_{\mathrm{H}}-\mathrm{M}_{\mathrm{Z}, \mathrm{N}}\right) \mathrm{c}^{2}. Given \ln ^{119}=118.9058 \mathrm{u}, \mathrm{Sn}^{120}=119.902199 \mathrm{u},  \mathrm{Sb}^{121}=120.903824 \mathrm{u},  \mathrm{H}^{1}=1.0078252 \mathrm{u}
(ii) What does the existence of magic number indicate?

i) The proton separation energy is given by, $\mathrm{SpSn}=(\mathrm{M} 119.70+\mathrm{Mh}-\mathrm{M} 120.70) \mathrm{c}^{2}=0.0114362 \mathrm{c}^{2}$ Similarly we have, $\mathrm{SpSp}=(\mathrm{M}...

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Before the neutrino hypothesis, the beta decay process was thought to be the transition \mathrm{n} \rightarrow \mathrm{p}+\mathrm{e}^{-}. If this was true, show that if the neutron was at rest, the proton and electron would emerge with fixed energies and calculate them. Experimentally, the electron energy was found to have a large range.

It is given that neutron was at rest before $\beta$ decay from neutron. So, energy of neutron $=$ $\mathrm{E}_{\mathrm{n}}=\mathrm{m}_{\mathrm{n}} \mathrm{c}^{2}$. Momentum of neutron...

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The deuteron is bound by nuclear forces just as \mathrm{H}-atom is made up of \mathrm{p} and e bound by electrostatic forces. If we consider the force between neutron and proton in deuteron as given in the form of a Coulomb potential but with an effective charge \mathrm{e}^{\prime}: F=\frac{1}{4 \Pi \epsilon_{0}} \frac{e^{\prime 2}}{r} estimate the value of \left(\mathrm{e}^{\prime} / \mathrm{e}\right) given that the binding energy of a deuteron is 2.2 \mathrm{MeV}.

The binding energy of $\mathrm{H}$ atom is given as $\mathrm{E}=13.6 \mathrm{eV}$ The reduced $\mathrm{m}^{\prime}$ is given as $918 \mathrm{~m}$ The mass of a neutron or a proton is given as...

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Deuteron is a bound state of a neutron and a proton with a binding energy B = 2.2 MeV. A γ -ray of energy E is aimed at a deuteron nucleus to try to break it into a (neutron + proton) such that the n and p move in the direction of the incident γ-ray. If E = B, show that this cannot happen. Hence calculate how much bigger than B must E be for such a process to happen.

The binding energy of a deuteron is given as $B = 2.2 MeV$ The kinetic energies of neutron and proton be $K_n$ and $K_p$ $p_n$ and $p_p$ are the momentum of neutron and proton $E - B = K_n + K_p$ B...

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Sometimes a radioactive nucleus decays into a nucleus which itself is radioactive. An example is
Sulphur^{38}\frac{\text { half-life }\longrightarrow}{=2.48 h}Cl^{38}\frac{\text { half-life }\longrightarrow}{=0.62 h}Ar^{38}(Stable)
Assume that we start with 1000 38S nuclei at time t=0. The number of Cl^{38} is of count zero at t=0 and will again be zero at t=\infty. At what value of t, would the number of counts be a maximum?

Let the disintegration constants for $S^{38}$ and $Cl^{38}$ be $\lambda_ 1$ and $\lambda_ 2$ respectively. $\mathrm dN_1 / \mathrm{dt}=-\lambda N_{1}$ $\mathrm dN_2 / \mathrm{dt}=$ rate of decay of...

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Are the nucleons fundamental particles, or do they consist of still smaller parts? One way to find out is to probe a nucleon just as Rutherford probed an atom. What should be the kinetic energy of an electron for it to be able to probe a nucleon? Assume the diameter of a nucleon to be approximately 10^{-15} \mathrm{~m}.

$\lambda=\mathrm{h} / \mathrm{p}$ and, kinetic energy $=$ potential energy $\mathrm{E}=\mathrm{hc} / \lambda$ Kinetic energy of an electron can be calculated as, $\mathrm{KE}=\mathrm{PE}=\mathrm{hc}...

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A piece of wood from the ruins of an ancient building was found to have a \mathrm{C}^{14} activity of 12 disintegrations per minute per gram of its carbon content. The C^{14} activity of the living wood is 16 disintegrations per minute per gram. How long ago did the tree, from which the wooden sample came, die? Given the half-life of \mathrm{C}^{14} is 5760 years.

$\mathrm{C}^{14}$ activity of a piece of wood from the ruins is given as $\mathrm{R}=12 \mathrm{dis} / \mathrm{min}$ per gram $\mathrm{C}^{14}$ activity of a living wood is given as...

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Consider a radioactive nucleus A which decays to a stable nucleus \mathrm{C} through the following sequence: \mathrm{A} \rightarrow \mathrm{B} \rightarrow \mathrm{C} Here \mathrm{B} is an intermediate nuclei which is also radioactive. Considering that there are \mathrm{N}_{0} atoms of A initially, plot the graph showing the variation of number of atoms of A and B versus time.

  At $\mathrm{t}=0,$ $\mathrm{~N}_{\mathrm{A}}=\mathrm{N}_{0}$ As time passes, $N_A$ decreases exponentially, while the number of atoms in B increases, reaches its maximum, and then decays to...

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