$A$ nucleus $_n{X^m}$ emits one $\alpha$ particle and two $\beta$ particles. The resulting nucleus is

$\beta$-rays emitted by a radioactive material are

Assertion: ${}_{Z}{X^{A}}$ undergoes $2\alpha$-decays,$2\beta$-decays,and $2\gamma$-decays,and the daughter product is ${}_{Z-2}{X^{A-8}}$.
Reason: In $\alpha$-decays,the mass number decreases by $4$ and the atomic number decreases by $2$. In $\beta$-decays,the mass number remains unchanged,but the atomic number increases by $1$.

$A$ $^{238}U$ nucleus decays by emitting an $\alpha$ particle of speed $v \ m/s$. The recoil velocity of the residual nucleus is (in $m/s$):

The correct order of ionizing capacity of $\alpha, \beta,$ and $\gamma$ rays is:

An element $X$ decays into element $Z$ by a two-step process:
$X \rightarrow Y + 4e$
$Y \rightarrow Z + 2e^{-}$
Then: