How many electrons can be accommodated in a sub-shell for which $n = 3, l = 1$?

The atom of the element having atomic number $14$ should have:

Identify which of the following sets of quantum numbers are not possible and explain why.
$(a) n = 0, l = 0, m_l = 0, m_s = +1/2$
$(b) n = 1, l = 0, m_l = 0, m_s = -1/2$
$(c) n = 1, l = 1, m_l = 0, m_s = +1/2$
$(d) n = 2, l = 1, m_l = 0, m_s = -1/2$
$(e) n = 3, l = 3, m_l = 3, m_s = +1/2$
$(f) n = 3, l = 1, m_l = 0, m_s = +1/2$

Which of the following is not a correct statement regarding the energies of orbitals?

What is the difference between the terms orbit and orbital?

The number of $s$-electrons present in an ion with $55$ protons in its unipositive state is