What is the electronic configuration of Chromium $(Z=24)$?

If the value of $(n+\ell)$ is not greater than $3$,which of the following subshells is not possible $-$

Which of the following sets of quantum numbers is possible?

For how many electrons in an atom is $n = 3, m_l = 1$ possible?

Arrange the electrons represented by the following sets of quantum numbers in the decreasing order of energy.
$(i) \ n = 4, l = 0, m_l = 0, m_s = +\frac{1}{2}$
$(ii) \ n = 3, l = 1, m_l = 1, m_s = -\frac{1}{2}$
$(iii) \ n = 3, l = 2, m_l = 0, m_s = +\frac{1}{2}$
$(iv) \ n = 3, l = 0, m_l = 0, m_s = -\frac{1}{2}$

Which one is the electronic configuration of $Fe^{2+}$?