Assertion : `sigma`-bond is strong white `pi` -bond is a weak bond.
Reason :Atomic rotate freely about `pi`-bond.

Options

A. If both the assertion and reason are true and reason is correct explanation of the assertion .
B. If both the assertion and reason are true but reason is not a correct explanation of the assertion .
C. If the assertion is true but the reason is false.
D. If both assertion and reason are false.

Answer

C

Explanation

Sigma bonding involves end to end overlapping of the two atomic orbitals e.g. between s and s, s and p and p and p orbitals.
Pi bonding `(pi)` involves sidewise overlapping of the two atomic orbital e.g. between p and p orbitals.
Overlapping of orbitals is more effective in ` sigma ` bonding then in ` pi`-bonding . Due to the geometry of overlapping or orbitals, rotation of one atom is not possible around `pi`-bonds.