Question

The mass number of a nucleus (except Hydrogen) is:

always less than its atomic number
never less than its atomic number
sometimes equal to its atomic number
sometimes less than and sometimes more than its atomic number

Answer 1

never less than its atomic no.

Mass no. = protons + neutrons

Answer 2

Never less than its atomic number
This is because the mass number is the sum of both the number of neutrons and protons, while the atomic number is the number of protons. Hydrogen is the only element without neutrons.