The atomic orbitals are progressively filled in order of increasing energy. This principle is called as

The number of $d$-electrons in $Fe^{2+}$ (atomic number of $Fe = 26$) is not equal to that of the

For both $2p$ and $3s$ orbitals,the value of $(n + l)$ is equal to $3$. Which of these has lower energy and why?

Few statements are given regarding nodes in the orbitals. Mark the statement which is not correct.

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 sets of quantum numbers is not possible?