Which of the following orbitals has a dumbbell shape?

If $n + l = 6$,then the total possible number of subshells would be

Which of the following statements concerning the four quantum numbers is false?

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

On what does the energy of hydrogen and hydrogen-like species depend? On what does it not depend?

The number of electrons with $(n+\ell)$ values equal to $3, 4$ and $5$ in an element with atomic number $(Z) = 24$ are respectively $(n =$ principal quantum number and $\ell =$ azimuthal quantum number).