What are the values of $n$ and $l$ for the $f$-subshell with the lowest energy?

For an atom with atomic number $Z = 25$,determine the total number of $s$ electrons present.

The maximum number of electrons which each sub-shell can occupy is

What is the correct order of energy of atomic orbitals in any given shell?

Consider the electronic configuration for neutral atoms:
$(i) \ 1s^22s^22p^63s^1$ $(ii) \ 1s^22s^22p^64s^1$
Which of the following statements is/are false?
$(a)$ Energy is required to change $(i)$ to $(ii)$
$(b)$ $(i)$ represents $Na$ atom
$(c)$ $(i)$ and $(ii)$ represent different elements
$(d)$ More energy is required to remove one electron from $(i)$ than $(ii)$

Arrange the orbitals of $H$ atom in the increasing order of their energy:
$3p_x, 2s, 4d_{xy}, 3s, 4p_z, 3p_y, 4s$