Find the exact orbital from the following for which $n=4$ and $l=1$.

If the nitrogen atom had electronic configuration $1s^7$,it would have energy lower than that of the normal ground state configuration $1s^2, 2s^2, 2p^3$ because the electrons would be closer to the nucleus. Yet,$1s^7$ is not observed because it violates:

$A$ subshell with $n=3$ and $l=2$ can accommodate a maximum of:

The wave function $(\Psi)$ of $2s$ is given by
$\Psi_{2s} = \frac{1}{2\sqrt{2\pi}} \left(\frac{1}{a_0}\right)^{3/2} \left(2 - \frac{r}{a_0}\right) e^{-r/2a_0}$
At $r = r_0$,a radial node is formed. Thus,$r_0$ in terms of $a_0$ is:

Which of the following represents the ground state of an atom?

The number of unpaired electrons in $Fe^{3+}$ $(Z = 26)$ is: