Two nuclei have their mass numbers in the ratio of 1:3. The ratio of their nuclear densities would be

(a) 1:3

(b) 3:1

(c) ${\left(3\right)}^{1/3}:1$

(d) 1:1

Concept Questions :-

Mass-energy equivalent
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Difficulty Level:

Two radioactive material ${X}_{1}$ and ${X}_{2}$ have decay constants $5\lambda$ and $\lambda$ respectively. If initially they have the same number of nuclei of ${X}_{1}$to that of after a time

(a)$\lambda$                                     (b)$\frac{1}{2}\lambda$

(c)$\frac{1}{4\lambda }$                                 (d)$\frac{e}{\lambda }$

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Difficulty Level:

The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an

(a) isobar of parent                                   (b) isomer of parent

(c) isotone of parent                                  (d) isotope of parent

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Types of decay
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Difficulty Level:

The binding energy per nucleon in deuterium and helium nuclei are  and  respectively. When two deuterium nuclei fuse to form a helium nucleus, the energy released in the fusion is

(a)                                          (b)

(c)                                           (d)

Concept Questions :-

Nuclear binding energy
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Difficulty Level:

The decay constant of a radio isotope is $\mathrm{\lambda }.$ If ${\mathrm{A}}_{1}$ and ${\mathrm{A}}_{2}$ are its activities at times ${\mathrm{t}}_{1}$ and ${\mathrm{t}}_{2}$ respectively, the number of nuclei which have decayed during the time $\left({\mathrm{t}}_{1}-{\mathrm{t}}_{2}\right)$

(a) ${\mathrm{A}}_{1}{\mathrm{t}}_{1}-{\mathrm{A}}_{2}{\mathrm{t}}_{2}$                                       (b) ${\mathrm{A}}_{1}-{\mathrm{A}}_{2}$

(c) $\frac{\left({\mathrm{A}}_{1}-{\mathrm{A}}_{2}\right)}{\mathrm{\lambda }}$                                         (d) $\mathrm{\lambda }\left({\mathrm{A}}_{1}-{\mathrm{A}}_{2}\right)$

Concept Questions :-

Types of decay
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Difficulty Level:

The activity of a radioactive sample is measured as ${N}_{0}$ counts per minute at t=0 and ${N}_{0}/e$ counts per minute at t=5 min.The time (in minute) at which the activity reduces to half its value is

(a) ${\mathrm{log}}_{e}2/5$                                                         (b)

(c)                                                          (d)

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Difficulty Level:

The mass of a ${}_{3}{}^{7}Li$ nucleus is 0.042u less than the sum of the masses of al  its nucleons.The binding energy per nucleon of ${}_{3}{}^{7}Li$ nucleus is nearly

(a) 46 MeV                              (b) 5.6 MeV

(c) 3.9 MeV                             (d) 23 MeV

Concept Questions :-

Nuclear binding energy
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Difficulty Level:

Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t=0, the number of P species are $4{N}_{0}$ and that of Q is and that of Q are ${N}_{0}.$Half-life of P(for conversion to R) is 1 min whereas that of Q is 2 min. Initially there are no nuclei of R present in the sample. When number of nuclei of P and Q are equal, the number of nuclei of R present in the sample would be:

(a)$3{N}_{0}$                                          (b)$\frac{9{N}_{0}}{2}$

(c)$\frac{5{N}_{0}}{2}$                                       (d)$2{N}_{0}$

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High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

Fusion reaction takes place at high temperature because

(a) atoms get ionised at high temperature

(b) kinetic energy is high enough to overcome the Coulomb repulsion between nuclei

(c) molecules break up at high temperature

(d) nuclei break up at high temperature

Concept Questions :-

Mass-energy equivalent
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Difficulty Level:

The half-life of a radioactive isotope X is 50 yr.

It decays to another element Y which is stable.

The two elements X and Y were found to be in

the ratio of 1:15 in a sample of a given rock.

The age of rock was estimated to be

(a) 200 yr

(b) 250 yr

(c) 100 yr

(d) 150 yr

Concept Questions :-