In the ground state of atomic $Fe \,(Z = 26)$,the spin-only magnetic moment is ...... $\times 10^{-1} \,BM$. (Round off to the nearest integer).
$[$Given $: \sqrt{3} = 1.73, \sqrt{2} = 1.41]$

The ground state energy of a hydrogen atom is $-13.6 \ eV$. Consider an electronic state $\Psi$ of $He^+$ whose energy,azimuthal quantum number,and magnetic quantum number are $-3.4 \ eV$,$2$,and $0$ respectively. Which of the following statement$(s)$ is(are) true for the state $\Psi$?
$(1)$ It has $2$ angular nodes
$(2)$ It has $3$ radial nodes
$(3)$ It is a $4d$ state
$(4)$ The nuclear charge experienced by the electron in this state is less than $2e$,where $e$ is the magnitude of the electronic charge.

The total number of electrons present in all the $s$-orbitals,all the $p$-orbitals,and all the $d$-orbitals of the cesium ion $(Cs^+)$ are respectively:

The sum of paired electrons present in $l = 2$ orbitals for the species $Fe^{2+}$,$Co^{2+}$,and $Ni^{2+}$ is .......

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

$A$ sub-shell with $l = 2$ can accommodate how many electrons?