A radioactive substance disintegrates 1/64 of initial value in 60 s. The half-life of this substance is

(1) 5 s         (2) 10 s          (3) 30 s          (4) 20 s

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The nucleus ${}_{6}C_{12}$ absorbs an energetic neutron and emits a beta particle $\left({\beta }^{-}\right)$. The resulting nucleus is

(1) ${}_{7}N_{14}$          (2) ${}_{7}N_{13}$         (3) ${}_{5}B_{13}$             (4) ${}_{6}C_{13}$

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Mass-energy equivalent
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If in a nuclear fusion  process, the masses of the fusion nuclei be  and the mass of the resultant nucleus be ${m}_{3}$, then [2004]

(1) ${m}_{3}={m}_{1}+{m}_{2}$                     (2) ${m}_{3}=\left|{m}_{1}-{m}_{2}\right|$

(3) ${m}_{3}<\left({m}_{1}+{m}_{2}\right)$                  (4) ${m}_{3}>\left({m}_{1}+{m}_{2}\right)$

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Mass-energy equivalent
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The nuclei of which one of the following pairs of nuclei are isotones? [2005]

(1)                   (2)

(3)                     (4)

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Mass-energy equivalent
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The counting rate observed from a radio active source at t = 0 second was 1600 counts per second and at t = 8 seconds it was 100 counts per second. The counting rate observed, as counts per second, at t = 6 seconds will be

(1) 400         (2) 300         (3) 200        (4) 150

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If ${N}_{0}$ is the original mass of the substance of half life period ${T}_{1/2}$= 5 years, then the amount of substance left after 15 years is [AIEEE 2012]

(1) ${N}_{0}$/8           (2) ${N}_{0}$/16           (3) ${N}_{0}$/2            (4) ${N}_{0}$/4

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The numbers of nuclei of a radioactive substance at time t = 0 are 1000 and 900 at time t = 2 s. Then number of nuclei at time t = 4 s will be

(1) 800            (2) 810             (3) 790             (4) 700

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A nucleus ${}_{Z}{}^{A}X$ has mass represented by m(A, Z). If ${m}_{p}$ and ${m}_{n}$ denote the mass of proton and neutron respectively and BE the binding energy (in MeV), then [2007]

(1) BE = [m(A, Z) - Z${m}_{p}$- (A - Z)${m}_{n}$${c}^{2}$

(2) BE = [Z${m}_{p}$+ (A - Z)${m}_{n}$- m(A,Z)] ${c}^{2}$

(3) BE = [Z${m}_{p}$+ A${m}_{n}$- m(A, Z)] ${c}^{2}$

(4) BE = m(A, Z) - Z${m}_{p}$- (A, Z)${m}_{n}$

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Nuclear binding energy
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The equation  is          (UP CPMT 2002)

(1) $\beta$-emission                (2) $\alpha$-emission

(3) ${e}^{-}$ capture                (4) fission

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Types of decay
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Half-lives of two radioactive substances A and B respectively 20 min and 40 min.  Initially, the samples of A and B have equal number of nuclei. After 80 min the ratio of remaining number of A and B nuclei is [1998]

(1) 1 : 16                         (2) 4 : 1

(3) 1 : 4                           (4) 1 : 1

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