What is the maximum number of electrons that may be present in all atomic orbitals with principal quantum number 3 and azimuthal quantum number 2?

On Mulliken scale, the average of ionization potential and electron affinity is known as _____.

Arrange the following in:
Decreasing ionic size:
Mg²⁺, O^2-, Na⁺, F^-

Arrange the following in:
Increasing first ionisation potential :
Mg, Al, Si, Na