Which of the following orbitals has two angular nodes?

The quantum numbers $+1/2$ and $-1/2$ for the electron spin represent

The probability of finding an electron in the $d_{xy}$ orbital is maximum along:

Identify the correct statements among the following:
$i. E_{2s}(H) > E_{2s}(Li) < E_{2s}(Na) > E_{2s}(K)$
$ii.$ The maximum number of electrons in the shell with principal quantum number $n$ is equal to $2n^2$.
$iii.$ Extra stability of half-filled subshell is due to smaller exchange energy.
$iv.$ Only two electrons,irrespective of their spin,may exist in the same orbital.

Explain $d$ orbital.

Which of the following orbitals has the least energy?