$A$ free neutron decays into a proton, an electron and

The electron emitted in beta radiation originates from

In the given reaction $_Z{X^A} \to _{Z+1}{Y^A} \to _{Z-1}{K^{A-4}} \to _{Z-1}{K^{A-4}}$,radioactive radiations are emitted in the sequence:

$A$ certain radioactive material $_ZX^A$ starts emitting $\alpha$ and $\beta$ particles successively such that the end product is $_{Z-3}Y^{A-8}$. The number of $\beta$ and $\alpha$ particles emitted are

$A$ nucleus ${ }_{Z} X^{A}$ emits an $\alpha$-particle with velocity $v$. The recoil speed of the daughter nucleus is

The unit '$rad$' is the correct measure for which of the following?