If the mass number of an atom is $A = 40$ and its electron configuration is $1{s^2},\;2{s^2},\;2{p^6},\;3{s^2},\;3{p^6}$, the number of neutrons and protons in its nucleus will be
22, 18
18, 22
20, 20
18, 18
The mass number of a nucleus is
Radius of $_2H{e^4}$ nucleus is $3 \,Fermi.$ The radius of $_{82}P{b^{206}}$ nucleus will be..........$fermi$
The radius of a nucleus of mass number $64$ is $4.8$ fermi. Then the mass number of another nucleus having radius of $4$ fermi is $\frac{1000}{x}$, where $x$ is______.
Define nuclear force.
If the total binding energies of ${ }_1^2 H ,{ }_2^4 He ,{ }_{26}^{56} Fe$ and ${ }_{92}^{235} U$ nucleiare $2.22,28.3,492$ and $1786 MeV$ respectively, identify the most stable nucleus of the following.