The electronic configuration of three elements $A$,$B$,and $C$ are given below. Stable form of $A$ may be represented by the formula:
$A : 1s^2, 2s^2, 2p^6$
$B : 1s^2, 2s^2, 2p^6, 3s^2, 3p^3$
$C : 1s^2, 2s^2, 2p^6, 3s^2, 3p^5$

Write about $p$-orbitals.

The electrons,identified by quantum numbers $n$ and $l$ as $(i) n = 4, l = 1$,$(ii) n = 4, l = 0$,$(iii) n = 3, l = 2$,$(iv) n = 3, l = 1$,can be placed in order of increasing energy,from the lowest to highest,as:

What is the maximum number of electrons that can have the quantum numbers $n = 5$ and $m_l = +2$?

The arrangement of orbitals on the basis of energy is based upon their $(n + l)$ value. Lower the value of $(n + l)$,lower is the energy. For orbitals having same values of $(n + l)$,the orbital with lower value of $n$ will have lower energy.
$(I)$ Based upon the above information,arrange the following orbitals in the increasing order of energy.
$(a)$ $1s, 2s, 3s, 2p$
$(b)$ $4s, 3s, 3p, 4d$
$(c)$ $5p, 4d, 5d, 4f, 6s$
$(d)$ $5f, 6d, 7s, 7p$
$(II)$ Based upon the above information,solve the questions given below:
$(a)$ Which of the following orbitals has the lowest energy? $4d, 4f, 5s, 5p$
$(b)$ Which of the following orbitals has the highest energy? $5p, 5d, 5f, 6s, 6p$

Which of the following sets of quantum numbers represent an impossible arrangement?
$n$ $l$ $m$ $m_s$