Answer the question on basis of passage given below:
The noble gases \(He\) to \(Rn\) have closed shell configuration and are monoatomic gases under normal conditions. Though mostly unreactive, direct reaction of Xe with \(F_2\) leads to a series of compounds with Xe oxidation numbers +2, +4 and +6. When certain compounds like phenol and quinol are crystallised in the presence of noble gas such as Ar, Kr and Xe a category of compound called clathrates are formed. In these the noble gas atoms are trapped in the cavities of the crystal lattices. The compounds which crystallise are known as hosts (H) while the noble gas atoms are called guests (G). The general formula of a clathrate compound is nHmG, where n is the number of host molecules and m is the number of guest atoms.
Which factors are responsible for making fluorine the strongest oxidising agent?
(A) Highest electronegativity
(B) High electron gain enthalpy
(C) High bond dissociation enthalpy
(D) Small size of fluorine
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B) and (D) only
Fluorine is the strongest oxidising agent because the change ½F2(g) → F−(aq) releases the most energy. Judging each factor:
(A) Highest electronegativity — True. Fluorine attracts electrons more strongly than any other element, so it readily accepts an electron.
(B) High electron gain enthalpy — True. A large amount of energy is released when F gains an electron (though slightly less than for Cl).
(C) High bond dissociation enthalpy — False. The F–F bond is unusually weak (low dissociation enthalpy, because of lone-pair repulsion in the small molecule). It is this low value that makes \( \ce{F2} \) easy to break up and so a strong oxidant.
(D) Small size of fluorine — True. The small \( \ce{F^{-}} \) ion has a very high hydration enthalpy, which releases extra energy in solution.
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):
Oxidation States and Trends in Chemical Reactivity – “… The ready acceptance of an electron is the reason for the strong oxidising nature of halogens. F2 is the strongest oxidising halogen and it oxidises other halide ions in solution or even in the solid phase.”