Assertion (A) Heavier elements of group 15 do not form `ppi-ppi` bonds.
Reason (R) Their atomic orbitals cannot have effective overiapping due to their large size. Choose the most suitable option.

A : Heavier elements of 14th group do not form p pi - p pi bonds . R : Atomic orbital of heavier elements are too large and do not have effective overlapping .

A : Heavier elements of 14th group do not form p pi - p pi bonds . R : Atomic orbital of heavier elements are too large and do not have effective overlapping .

Assertion : Carbon has unique ability to form p pi-p pi multiple bonds with itself and with other atomic of small size and high electronegativety. Reason : Heaviur elements of group 14th do not form p pi -p pi bonds because their atomic orbital are too large and diffuse to have effective sideways overapping.

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Heavy water is used for the study of reaction mechanism. Reason (R) : The rate of reaction for the cleavage of O - H bond is slower than that of O - D bond. Choose the most appropriate answer from the options given below :