Assertion : The heavier p-block element do not form strong `pi` bonds.
Reason : The heavier elements of p-block form `d pi - p pi` or `d pi - d pi` bonds

Options

A. Assertion is false but reason is true
B. Assertion is true but reason is false
C. Both assertion and reason are true, but reason is not a true explanation for assertion
D. Both assertion and reason are true and reason is the correct explanation for assertion

Answer

D

Explanation

The presence of the d-orbitals influences the chemistry of the heavier elements in a number of other ways. The combined effect of size and availability of d-orbitals considerably influences the ability of these elements to form `pi` bonds. The heavier elements do form `pi` bonds but this involves d orbitals `(d pi-p pi or d pi - d pi)`. As the d orbitals are of higher energy than the p orbitals, they contributes less to the overall stability of molecules than does `p pi- p pi` bonding of the second row elements.