Which of the following statements are correct?
A. \(F_2\) is less reactive than \(ClF\)
B. \(F_2\) is more reactive than \(ClF\)
C. \(F-F\) bond is weaker than \(Cl-F\) bond
D. \(F-F\) bond is stronger than \(Cl-F\) bond
Choose the correct answers from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → B and C only
The reactivity of a halogen or interhalogen depends on how easily its X–X′ bond breaks. Interhalogens are in general more reactive than the parent halogens because the X–X′ bond is weaker than the X–X bond. Fluorine is the exception: the F–F bond is very weak.
(A) F2 is less reactive than ClF — False. \( \ce{F2} \) is the most reactive of all; it is more reactive than ClF.
(B) F2 is more reactive than ClF — True. The weak F–F bond breaks very easily, so \( \ce{F2} \) reacts more readily than ClF.
(C) F–F bond is weaker than Cl–F bond — True. The very small F atoms hold their lone pairs close together; the strong lone pair–lone pair repulsion makes the F–F bond weak (158.8 kJ mol−1). The polar Cl–F bond is stronger.
(D) F–F bond is stronger than Cl–F bond — False. It is the opposite of (C).
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Properties – “… Their chemical reactions can be compared with the individual halogens. In general, interhalogen compounds are more reactive than halogens (except fluorine). This is because X–X′ bond in interhalogens is weaker than X–X bond in halogens except F–F bond.”