$A$ subshell with $n=3$ and $l=2$ can accommodate a maximum of:

Given below are two statements. One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$ : Energy of $2s$ orbital of hydrogen atom is greater than that of $2s$ orbital of lithium.
Reason $R$ : Energies of the orbitals in the same subshell decrease with increase in the atomic number.
In the light of the above statements,choose the correct answer from the options given below.

The number of radial nodes of $3s$ and $2p$ orbitals are respectively.

The principal quantum number of an atom represents:

The orbital diagram in which the Aufbau principle is violated is:
$2s$ $2p_x$ $2p_y$ $2p_z$

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