The ratio of the nuclear radii of the gold isotope ${}_{79}^{197}Au$ and the silver isotope ${}_{47}^{107}Ag$ is $ . . . . . . $.

$^{22}Ne$ nucleus after absorbing energy decays into two $\alpha$-particles and an unknown nucleus. The unknown nucleus is

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The nuclear density of nuclides ${ }_{5}^{10} B, { }_{3}^{6} Li, { }_{26}^{56} Fe, { }_{10}^{20} Ne$ and ${ }_{83}^{209} Bi$ can be arranged as $\rho_{ Bi }^{ N } > \rho_{ Fe }^{ N } > \rho_{ Ne }^{ N } > \rho_{ B }^{ N } > \rho_{ Li }^{ N }$.
Reason $R$: The radius $R$ of a nucleus is related to its mass number $A$ as $R = R_0 A^{1/3}$,where $R_0$ is a constant.
In the light of the above statements,choose the correct answer from the options given below:

The volume of a nucleus is directly proportional to

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

$A$ reaction between a proton and $_8^{18}O$ that produces $_9^{18}F$ must also liberate: