Read the following :
(i) The half-life period of a radioactive element X is same as the mean-life time of another radioactive element Y. Initially both of them have the same number of atoms. Then Y will decay at a faster rate the X.
(ii) The electron emitted in beta radiation originates from decays of a neutron in a nucleus
(iii) The half-life `"of"^( 215)` At is 100 ms. The time taken for the radioactivity of a sample `"of"^( 215)` At to decay to `1//16^(th)` of its initial value is 400 ms.
(iv) The volume (V) and mass (m) of a nucleus are related a V `prop`m.
(v) Given a sample of Radium - 226 having halflife of 4 days. Find the probability, a nucleus disintegrates within 2 half lives is 3/4. Select the correct code for above.

Answer

a. `2.03xx10^(20)`, b. `279xx10^(9)s^(-1)`