A) Both (a) and (R) are true and (R) is the correct explanation of
B) Both (A) and (R) are true but (R) is not the correct explanation of
C) Only (A) is true but (R) is not true
D) (A) is not true but (R) is true
Correct Answer: A
Solution :
On going down the group, the X?-X bond dissociation energy gradually decreases. So F?F bond dissociation energy should be greater than that of bromine but this is not so. The actual bond dissociation energy of fluorine molecule is, however, surprisingly low. This is attributed to the fact that F atom is very small and non-bonding electrons of F are nearer to each other, resulting in a much greater lone pair-lone pair repulsion, which weakens the covalent bond and lowers its dissociation energy. This repulsion is not so great in relatively larger halogen molecules like bromine where the lone pairs are at a greater average distance from each other.
You need to login to perform this action.
You will be redirected in
3 sec
