Which of the following configurations is correct for iron $(Fe)$?

The angular part of the wave function for an orbital is given by $\psi_{(\theta, \phi)} = \left( \frac{15}{4\pi} \right)^{1/2} \sin \theta \cos \theta \sin \phi$,where $\theta$ is the angle from the $z$-axis. The angular node$(s)$ are:

Figure $1$ shows the electron density distribution for a $2s$ orbital. Figure $2$ shows the radial wave function plot for a $2s$ orbital. Which of the following points $(A, B, C, D)$ in Figure $2$ most accurately represents the spherical nodal surface as shown in Figure $1$?

What is the number of unpaired electrons in the electronic configuration of the $N^{+2}$ ion?

In a potassium atom,the electronic energy levels are in the following order:

The number of unpaired electrons in the $p$-subshell of oxygen atom is