The radioactivity of a sample is `l_(1)` at a time `t_(1)` and `l_(2)` time `t_(2)`. If the half-life of the sample is `tau_(1//2)`, then the number of nuclei that have disintegrated in the time `t_(2)-t_(1)` is proportional to

Options

A. `(l_(1)-t_(2)-l_(2)t_(1)`
B. `l_(1)-l_(2)`
C. `(l_(1)-l_(2))/(tau_(1//2))`
D. `(l_(1)-l_(2))tau_(1//2)`

Answer

D

Explanation

A beta minus particle `(beta^(-))` is an electron. Emission of `beta^(-)` involves transformation of a neutron into a proton, an electron and a third particle called an anti-neutrino `(overline(v))`.
`""_(15)P^(32)to""_(16)S^(32)+""_(-1)beta^(0)+overline(v)`