In the nucleus of ${ }_{11} N a^{23}$, the number of protons, neutrons and electrons are
$11,12,0$
$12,11,0$
$23,12,11$
$23,11,12$
Atomic number of a nucleus is $Z$ and atomic mass is $M.$ The number of neutron is
What percentage of the mass of the nucleus is the mass of the nucleus ?
The ratio of the density of oxygen nucleus $\left({ }_8^{16} O \right)$ and helium nucleus $\left({ }_2^4 He \right)$ is
How the radius of the nucleus is estimated ? Write its relation to radius and atomic mass number.
Radius of the second Bohr obit of singly ionised helium atom is ......... $Å$