$M_n$ and $M_p$ represent the mass of a neutron and a proton, respectively. If an element having atomic mass $M$ has $N$ neutrons and $Z$ protons, then the correct relation is:

Degenerate electron pressure will not be sufficient to prevent the core collapse of a white dwarf if its mass becomes $n$ times the solar mass. The value of $n$ is:

The binding energy of a nucleon in a nucleus is of the order of a few

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ The binding energy per nucleon is practically independent of the atomic number for nuclei of mass number in the range $30$ to $170$.
Reason $R:$ Nuclear force is short-ranged.
In the light of the above statements, choose the correct answer from the options given below:

$A$ nucleus with mass number $242$ and binding energy per nucleon as $7.6\,MeV$ breaks into two fragments,each with mass number $121$. If each fragment nucleus has a binding energy per nucleon of $8.1\,MeV$,the total gain in binding energy is $........MeV$.

In the nuclear reaction $_1^2H + _1^3H \to _2^4He + _0^1n$, if the binding energies of $_1^2H$, $_1^3H$, and $_2^4He$ are respectively $a$, $b$, and $c$ (in $MeV$), then the energy (in $MeV$) released in this reaction is: