A photon of hard gamma radiation knocks a proton out of ${ }_{12}^{24}\mathrm{Mg}$ to form

The mass number and charge number both decrease due to the knocking out of proton.

A photon of hard gamma radiation knocks a proton out of${ }_{12}^{24}\mathrm{Mg}$ nucleus.

Removal of one proton will decrease the atomic number and atomic mass by one. So${ }_{12}^{24}\mathrm{Mg}$ 

Will Form

 ${ }_{11}^{23}\mathrm{Na}$

Nucleus of 

${ }_{11}^{23}\mathrm{Na}$