Which atomic species cannot be used as a nuclear fuel?

In the decay,${}_Z^AX \to {}_{6}^{12}C + {}_{+1}^{0}\beta$,identify the values of $A$ and $Z$.

$_{90}Th^{228}$ emits four alpha and one beta particles. The number of neutrons in the daughter element is:

The number of neutrons in the parent nucleus which gives $N^{14}$ on $\beta$-emission and the parent nucleus is

Match List-$I$ and List-$II$ and choose the correct option using the codes given below:

List-$I$ (Nuclear reactor component)	List-$II$ (Used substance)
$1$. Moderator	$(a)$ Uranium
$2$. Control rods	$(b)$ Graphite
$3$. Fuel rods	$(c)$ Boron
$4$. Coolant	$(d)$ Lead
	$(e)$ Sodium

The atomic mass of lead is $208$ and atomic number is $82$. The atomic mass of bismuth is $209$ and atomic number is $83$. The ratio of $n/p$ in the atom is