Calculate the value of $(n + l)$ for the $3d$ orbital.

The correct decreasing order of energy for the orbitals having the following set of quantum numbers:
$A$. $n=3, \ell=0, m=0$
$B$. $n=4, \ell=0, m=0$
$C$. $n=3, \ell=1, m=0$
$D$. $n=3, \ell=2, m=1$

The orbital angular momentum of an electron in $3s$ orbital is $\frac{xh}{2\pi}$. The value of $x$ is . . . . . . .

Match the entries in Column $I$ with the correctly related quantum number$(s)$ in Column $II$.

Column $I$	Column $II$
$A$. Orbital angular momentum of the electron in a hydrogen-like atomic orbital	$p$. Principal quantum number
$B$. $A$ hydrogen-like one-electron wave function obeying Pauli principle	$q$. Azimuthal quantum number
$C$. Shape,size and orientation of hydrogen-like atomic orbitals	$r$. Magnetic quantum number
$D$. Probability density of electron at the nucleus in hydrogen-like atom	$s$. Electron spin quantum number

The maximum probability of finding an electron in the $d_{xy}$ orbital is

Using $s$,$p$,$d$,and $f$ notations,describe the orbital with the following quantum numbers:
$(a)$ $n=1$,$l=0$
$(b)$ $n=3$,$l=1$
$(c)$ $n=4$,$l=2$
$(d)$ $n=4$,$l=3$