What is the total number of unpaired electrons present in the observed electronic configuration of $Cr$ $(Z=24)$?

Which of the following ions does not have the same electronic configuration as $Ne$?

Write the increasing order of energy for $2p, 3p, 4p, 5p$ orbitals.

The electronic configuration of $Sc$ $(Z = 21)$ is:

$2p$ orbitals have

The wave function $R_{2,0}$ for hydrogen atom is $R_{2,0} = K(2 - r/a_0) \exp(-r/2a_0)$,where $K$ is a constant. The distance $r$ at which $R_{2,0}$ exhibits a nodal point is at: