${ }_{92}^{238} U$ and ${ }_{90}^{236} Th$ are $\qquad$ of each other.

Nuclear reactions are given as $(i)$ $(n, p) {}_{16}S^{32} \to {}_{15}P^{32}$,$(ii)$ $(p, \alpha) {}_{8}O^{16} \to {}_{9}F^{19}$,$(iii)$ ${}_{7}N^{14} + ? \to {}_{6}C^{14} + {}_{1}H^{1}$. The missing particles or nuclides in these reactions are respectively:

$A$ heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio $3: 1$. The ratio of radii of the fragments is

$A$ nucleus disintegrates into two nuclear parts,in such a way that the ratio of their nuclear radii is $1: 2^{1/3}$. Their respective speeds have a ratio of $n: 1$. The value of $n$ is $.....$.

The volume of a nucleus is proportional to ........ (where,$A$ is the mass number of the nucleus).

The force between a proton and a proton in a nucleus is .......