If the nuclear radius of A27l is 3.6 Fermi, the approximate nuclear radius of C64u in Fermi is

(a)2.4                                         (b)1.2

(c)4.8                                         (d)3.6

Concept Questions :-

Mass-energy equivalent
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A mixture consists of two radioactive materials A1 and A2 with half lives of 20 s and 10 s respectively.Initially the mixture has 40g of A1 and 160g of A2. The amount of the two in the mixture will become equal after

(a)60 s                                      (b)80 s

(c)20 s                                      (d) 40 s

Concept Questions :-

Radioactivity
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The half life of a radioactive nucleus is 

50 days. The time interval (t2-t1) between 

the time t2 when 23 of it has decayed and 

the time t1 when 13 of it had decayed is

(a) 30 days

(b) 50 days

(c) 60 days

(d) 15 days

Concept Questions :-

Radioactivity
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The power obtained in a reactor using U235

disintegration is 1000 kW. The mass decay

of U235 per hour is

(a) 20 μg

(b) 40 μg

(c) 1 μg

(d) 10 μg

Concept Questions :-

Mass-energy equivalent
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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 :-

Radioactivity
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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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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 4N0 and that of Q is and that of Q are N0.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)3N0                                          (b)9N02

(c)5N02                                       (d)2N0

Concept Questions :-

Radioactivity
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The mass of a L37i nucleus is 0.042u less than the sum of the masses of al  its nucleons.The binding energy per nucleon of L37i 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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The activity of a radioactive sample is measured as N0 counts per minute at t=0 and N0/e counts per minute at t=5 min.The time (in minute) at which the activity reduces to half its value is 

(a) loge2/5                                                         (b) 5loge 2

(c) 5 log10 2                                                         (d) 5 loge 2

Concept Questions :-

Radioactivity
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The decay constant of a radio isotope is λ. If A1 and A2 are its activities at times t1 and t2 respectively, the number of nuclei which have decayed during the time (t1-t2)

(a) A1t1-A2t2                                       (b) A1-A2

(c) (A1-A2)λ                                         (d) λ(A1-A2) 

Concept Questions :-

Types of decay
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