The principal quantum number represents:

For $s-$orbitals,since $\psi$ (orbital) is independent of angles,the probability $(\psi^2)$ is

The orbital angular momentum of an electron in an $s$ orbital is:

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.

What is the number of unpaired electrons present in the ground state of Silicon $(Si)$ and Chromium $(Cr)$, respectively?

Consider the hypothetical situation where the azimuthal quantum number,$l$,takes values $0, 1, 2, \ldots, n+1$,where $n$ is the principal quantum number. Then,the element with atomic number