Why do real gases deviate from the ideal gas laws at low temperatures?

The volume occupied by molecules becomes a significant part of the total volume.

Masses of individual particles increase as kinetic energy decreases.

Attractions between molecules cause a reduction in volume.

What are the first two quantum numbers for the electrons located in subshell 4d? what are the first three quantum numbers for the electrons located in subshell 2s? how many electrons can be held in a sublevel l = 3? how many electrons can be held in the energy level n = 4? how many electrons in an atom can share the quantum numbers n = 4 and l = 3?