The order of filling of electrons in the orbitals of an atom will be

List the quantum numbers ($l$ and $m_{l}$) for an electron in a $3d$ orbital.

The hydrogen-like species $Li^{2+}$ is in a spherically symmetric state $S_1$ with one radial node. Upon absorbing light,the ion undergoes transition to a state $S_2$. The state $S_2$ has one radial node and its energy is equal to the ground state energy of the hydrogen atom.
$1.$ The state $S_1$ is
$(A)$ $1s$ $(B)$ $2s$ $(C)$ $2p$ $(D)$ $3s$
$2.$ Energy of the state $S_1$ in units of the hydrogen atom ground state energy is
$(A)$ $0.75$ $(B)$ $1.50$ $(C)$ $2.25$ $(D)$ $4.50$
$3.$ The orbital angular momentum quantum number of the state $S_2$ is
$(A)$ $0$ $(B)$ $1$ $(C)$ $2$ $(D)$ $3$
Give the answer for questions $1, 2$ and $3.$

The electronic configuration,which obeys Hund's rule for the ground state of carbon atom is

The number of unpaired electrons in $Fe^{3+}$ $(Z = 26)$ is:

The magnetic quantum number for the valence electron of sodium is