$A$ radioactive nucleus will not emit

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

Which metal is used in radiation shielding?

An atom has a mass number of $232$ and an atomic number of $90$. How many $\alpha$-particles should it emit after the emission of two $\beta$-particles,so that the resulting atom has a mass number of $212$ and an atomic number of $82$?

The element with atomic number $84$ and mass number $218$ changes to another element with atomic number $84$ and mass number $214$. The number of $\alpha$ and $\beta$-particles emitted are respectively:

In the reaction $_{93}Np^{239} \xrightarrow{} _{94}Pu^{239} + (?)$,the missing particle is