Question

Which of the following orbitals can not undergo hybridisation amongst themselves?
(I) $3d$, $4s$
(II) $3d$, $4d$
(III) $3d$, $4s$ and $4p$
(IV) $3s$, $3p$ and $4s$

• A. only II
• B. II and III
• C. I, II and IV
• D. II and IV

Answer 1

Answer: (D)

II and IV

The order in which s, p, d and f orbitals are filled with electrons are governed by their energy levels. The lower energy orbital is filled first, followed by the very next orbital [1s energy is less than 2s] hence, 3d, 4d and 3s, 3p, 4s can not undergo hybridisation among themselves, because these orbitals are not in the sequential order of increasing energy.