The electronic configuration $1s^{2}\, 2s^{2}\, 2p^{5}\, 3s^{1}$ represents:

Electronic configuration of $Cu$ $(Z = 29)$ is

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:

Identify the pair of elements in which the ratio of the number of $s$-electrons to $p$-electrons is $2:3$.

Identify the incorrect statement from the following.

Which of the following is not a correct statement regarding the energies of orbitals?