Arrange the energy of the $2s$ orbital for hydrogen,lithium,sodium,and potassium in increasing order.

Describe the orbitals with the following quantum numbers using $s, p, d, f$ notation:
$(a) n = 1, l = 0$
$(b) n = 3, l = 1$
$(c) n = 4, l = 2$
$(d) n = 4, l = 3$

How many orbitals are present in the $4^{th}$ shell with $\ell = 2$?

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

What is the number of unpaired electrons present in $d$ orbitals of $Cr (Z=24)$ to have extra stability?

The quantum numbers of four electrons are given below:
$I. \ n = 4, l = 2, m_l = -2, m_s = -1/2$
$II. \ n = 3, l = 2, m_l = 1, m_s = +1/2$
$III. \ n = 4, l = 1, m_l = 0, m_s = +1/2$
$IV. \ n = 3, l = 1, m_l = 1, m_s = -1/2$
The correct order of their increasing energies will be: