Which of the following sets of orbitals may degenerate?

Identify the correct statements:
a) In an atom,the maximum number of electrons with $n=4$ and $m_s=+\frac{1}{2}$ is $16$.
b) There are $4$ subshells associated with $n=5$.
c) $n=2, l=1, m_l=0$ and $m_s=-\frac{1}{2}$ is a possible set of quantum numbers.
d) The number of radial nodes for $3s$ orbital is $2$.

Given below are the quantum numbers for $4$ electrons.
$A. \; n = 3, l = 2, m_l = 1, m_s = +1/2$
$B. \; n = 4, l = 1, m_l = 0, m_s = +1/2$
$C. \; n = 4, l = 2, m_l = -2, m_s = -1/2$
$D. \; n = 3, l = 1, m_l = -1, m_s = +1/2$
The correct order of increasing energy is

The correct electronic configuration of $Fe^{3+}$ $[Z=26]$ is:

Describe the orbitals with the following quantum numbers using $s, p, d, f$ notations:
$(a) \ n = 2, l = 1$
$(b) \ n = 4, l = 0$
$(c) \ n = 5, l = 3$
$(d) \ n = 3, l = 2$

For an electron in $2s$ and $2p$ orbitals,the orbital angular momentum values,respectively,are $:$