Is it possible to have a relative atomic mass less then 24 or more than 26

I think Magnesium not sure because the relative atomic mass of magnesium is 24,31.

There is one s orbital, and there are three p orbitals, five d orbitals, and seven f orbitals. thus, the answer is b. do not confuse the number of orbitals in a subshell with the number of electrons the subshell can hold. each orbital can hold two electrons, so the capacity of an nf subshell is 14 electrons.