A positron is emitted from ${ }^{23} \mathrm{Na}_{11}$. The ratio of the atomic mass and atomic number of the resulting nuclide is

Ratio of nuclear radii of ${ }^{135} Cs$ to ${ }^{40} Ca$ is

Assertion $(A):$ Forces acting between proton-protn $\left(f_{p p}\right)$, proton-neutron $\left(f_{p p}\right)$ and neutron-neutron $\left(f_{n n}\right)$ are such that $f_{p p} < f_{p n}=f_{n n}$

Reason $(R):$ Electrostatic force of repulsion between two protons reduces net nuclear forces between them.

The graph between $log\, R$ and $log\, A$ where $R$ is the nuclear radius and $A$ is the mass number is

The mass density of a nucleus varies with mass number $A$ as

The deuteron is bound by nuclear forces just as $H-$ atom is made up of $p$ and $e$ bound by electrostatic forces. If we consider the force between neutron and proton in deuteron as given 1 e 2 in the form of a Coulomb potential but with an effective charge $e' \,:\,F = \frac{1}{{4\pi { \in _0}}}\frac{{e{'^2}}}{r}$ . estimate the value of $(e'/e)$ given that the binding energy of a deuteron is $2.2\, MeV.$