Explain the differences between the $1s$ and $2s$ orbitals based on their probability density plots and radial distribution.

Consider the Argon atom. For how many electrons does this atom have $m = 1$?

What are core electrons and valence electrons?

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

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.

According to the Aufbau principle,which orbital is filled with electrons immediately after the $5f$ orbital?