Which of the following orbitals are not possible?
1p, 2s, 3f and 4d

Explanation

(i) The first shell has only one sub-shell, i.e., 1s, which has only one orbital, i.e., 1s orbital. Therefore, 1p orbital is not possible.
(ii) The second sub-shell has two subshells, i.e., 2s and 2p. Therefore, 2s orbitals are possible.
(iii) The third subshell has three subshells, i.e., 3s, 3p and 3d. Therefore, 3f-orbitals are not possible
(iv) The fourth shell has four subshells has four subshells, i.e., 4s, 4p 4d and 4f. Therefore, 4d-orbitals are possible