Which has the least penetrating power?

In the decay sequence:
$^{238}_{92}U$ $\xrightarrow{- x_1} ^{234}_{90}Th$ $\xrightarrow{- x_2} ^{234}_{91}Pa$ $\xrightarrow{- x_3} ^{234}_{92}Z$ $\xrightarrow{- x_4} ^{230}_{90}Th$
$x_1, x_2, x_3$ and $x_4$ are particles/radiation emitted by the respective isotopes. The correct option$(s)$ is/are-
$(1)$ $Z$ is an isotope of uranium
$(2)$ $x_2$ is $\beta^{-}$
$(3)$ $x_1$ will deflect towards negatively charged plate
$(4)$ $x_3$ is $\gamma$-ray

Of the following radiations,the one most easily stopped by air is

Tritium undergoes radioactive decay giving

$_{72}^{180}X$ $\xrightarrow{2\alpha}$ $\xrightarrow{\beta}$ $\xrightarrow{\gamma} _{Z}^{A}X'$. The values of $Z$ and $A$ are:

During $\beta$-decay: