The principal quantum number of an atom is related to the:

There is no difference between a $2p$ and a $3p$ orbital regarding

Which of the following elements has a half-filled valence shell?

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.

Not considering the electronic spin,the degeneracy of the second excited state $(n=3)$ of $H$ atom is $9$,while the degeneracy of the second excited state of $H^{-}$ is

Which of the following combination of statements is true regarding the interpretation of the atomic orbitals?
$1$. An electron in an orbital of high angular momentum stays further away from the nucleus than an electron in an orbital of lower angular momentum.
$2$. For a given value of the principal quantum number,the size of the orbit is inversely proportional to the azimuthal quantum number.
$3$. According to wave mechanics,the ground state angular momentum is equal to $\frac{h}{2\pi}$.
$4$. The plot of $\Psi$ vs $r$ for various azimuthal quantum numbers shows peak shifting towards higher $r$ values.