Which statement is true regarding the hydrogen atom?

The $3p$ orbital has ........

The number of correct statements from the following:
$A.$ For $1s$ orbital,the probability density is maximum at the nucleus.
$B.$ For $2s$ orbital,the probability density first increases to maximum and then decreases sharply to zero.
$C.$ Boundary surface diagrams of the orbitals enclose a region of $100\%$ probability of finding the electron.
$D.$ $p$ and $d$-orbitals have $1$ and $2$ angular nodes respectively.
$E.$ Probability density of $p$-orbital is zero at the nucleus.

The electronic configuration $1s^2 2s^2 2p_x^1 2p_y^1 2p_z^1$ corresponds to which of the following elements?

If an atom has $13$ electrons in the $M$ shell and $1$ electron in the $N$ shell,then the number of unpaired electrons in that atom is ...

What is the maximum number of electrons that can be accommodated in an orbital with $l = 3$?