Which is the best description of behaviour of bromine in the reaction given below?
\(H_2O + Br_2 \longrightarrow HBr + HOBr\)
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Both oxidised and Reduced
Oxidation states of bromine in the reaction:
\( \displaystyle \ce{H2O} + \overset{0}{\ce{Br2}} \longrightarrow \overset{-1}{\ce{HBr}} + \overset{+1}{\ce{HOBr}} \)
0 → −1 in HBr: one Br atom gains an electron and is reduced.
0 → +1 in HOBr: the other Br atom loses an electron and is oxidised.
The same element is oxidised and reduced at the same time, so this is a disproportionation reaction.
Why the other options are incorrect
Option (1) Proton accepted only — Incorrect. \( \ce{Br2} \) is not acting as a base; its oxidation state changes.
Option (3) Oxidised only — Incorrect. Ignores the Br that goes to −1 in HBr.
Option (4) Reduced only — Incorrect. Ignores the Br that goes to +1 in HOBr.
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):
Chemical Properties – …
