Which graph in the following diagrams correctly represents the potential energy $U$ of a pair of nucleons as a function of their separation $r$?

The order of magnitude of the density of a uranium nucleus is: (Given: ${m_p} = 1.67 \times 10^{-27} \ kg$)

In the nuclear reaction ${ }_{7}^{14} N + X \rightarrow { }_{6}^{14} C + { }_{1}^{1} H$, the $X$ will be

Nuclear reactions are given as:
$(i) \, \square (n, p) {_{15}}P^{32}$
$(ii) \, \square (p, \alpha) {_{8}}O^{16}$
$(iii) \, {_{7}}N^{14} (\square, p) {_{6}}C^{14}$
The missing particles or nuclides (in box $\square$) in these reactions are respectively:

The sodium nucleus $_{11}^{23}\text{Na}$ contains

Two nucleons are at a separation of $1 \times 10^{-15} \ m$. The net force between them is $F_1$ if both are neutrons,$F_2$ if both are protons,and $F_3$ if one is a proton and the other is a neutron. In such a case: