The number of unpaired electrons in the $Fe^{2+}$ ion is

The atomic weight of an element is twice its atomic number. If the $2p$ subshell contains three electrons,the element is .......

The correct ground state electronic configuration of chromium atom is

The angular wave function $A(\theta, \phi)$ for a given atomic orbital is $\frac{1}{2}\sqrt{\frac{3}{\pi}}\cos \theta$ in the polar coordinate system. Identify the orbital.

An electron is in one of the $3d$ orbitals. Give the possible values of $n, l,$ and $m_l$ for this electron.

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