Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R. Assertion A:…
Redox Reactions · Class 11 · JEE Main Previous Year Question
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Permanganate titrations are not performed in presence of hydrochloric acid. Reason R: Chlorine is formed as a consequence of oxidation of hydrochloric acid.
In the light of the above statements, choose the correct answer from the options given below:
- a✓
Both A and R are true and R is the correct explanation of A
- b
Both A and R are true but R is NOT the correct explanation of A
- c
A is true but R is false
- d
A is false but R is true
Both A and R are true and R is the correct explanation of A
Step 1 — Evaluate Assertion A:
is a strong oxidising agent. In the presence of HCl:
oxidises to , consuming extra beyond what is needed for the analyte. This gives erroneous (higher) results.
Therefore, permanganate titrations are NOT performed in HCl medium — is used instead. Assertion A is TRUE ✓
Step 2 — Evaluate Reason R:
The reason is exactly as stated: oxidises HCl, producing . This is the correct chemical explanation for why HCl cannot be used. Reason R is TRUE ✓ and is the correct explanation of A.
Answer: Option (1) — Both A and R are true, R is the correct explanation of A
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