When an alpha particle of mass m moving with velocity v bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucleus depends on mass as,
m
m
The half-life to a radioactive nucleus is 50 days. The time interval (t_{2}-t_{1}) between the time t_{2} when 2/3 of it has decayed and the time t_{1} when 1/3 of it had decayed is
30 days
50 days
60 days
15 days
If the nuclear radius of^{27} Al is 3.6 Fermi, the approximate nuclear radius of ^{64}Cu in Fermi is
2.4
1.2
4.8
4.8
A mixture consists of two radioactive materials A_{1} and A_{2} with half-lives of 20 s and 10 s respectively. Initially, the mixture has 40 g of A_{1} and 160 g of A_{2}. The amount of the two in the mixture will become equal after
60 s
80 s
20 s
20 s
The binding energy per nucleon of nuclei are 5.60 MeV and 7.06 MeV, respectively. In the nuclear reaction, , the value of energy Q released is,
19.6 MeV
-2.4 MeV
8.4 MeV
8.4 MeV
A radio isotope X with a half life 1.4 x 10^{9} yr decays of Y which is stable. A sample of the rock from a cave was found to contain X and Y in the ratio 1:7. The age of the rock is,
1.96 x 10^{9} yr
3.92 x 10^{9} yr
4.20 x 10^{9} yr
4.20 x 10^{9} yr
The half-life of radioactive isotope X is 20 yr. It decays to another element Y which is stable.The two elements X and Y were found to be in the ratio 1:& in a sample of given rock is estimated to be
40 yr
60 yr
80 yr
80 yr
A radioactive nucleus of mass M emits a photon of frequency v and the nucleus recoils.The recoil energy will be
h^{2}v^{2} / 2Mc^{2}
zero
hv
hv
The power obtained in a reactor using U^{235} disintegration is 1000kW. The mass decay of U^{235} per hour is
20 μg
40 μg
1 μg
1 μg