What is the mass number of an atom which contains 28 protons, 28 electrons, and 34 neutrons?

The mass number of the atom = 62

Given,

The number of protons,  $n_p=28$ 

The number of electrons, $n_e=28$

The number of neutrons, $n_n=34$ 

The mass number of the atoms =?

As we know,

 The mass number is defined as the sum of the number of protons and the number of neutrons.

The electrons are not included because they have almost negligible mass and are considered nearly equal to zero.

Therefore,

 Mass number =$n_p+n_n$ 

Mass number =28+34=62

Hence, the mass number of the atom = 62

Hence, option A is correct.