Given below are two statements: Statement I: In the titration between strong acid and weak base, methyl orange is…
Ionic Equilibrium · Class 11 · JEE Main Previous Year Question
Given below are two statements:
Statement I: In the titration between strong acid and weak base, methyl orange is suitable as an indicator. Statement II: For titration of acetic acid with NaOH, phenolphthalein is not a suitable indicator.
Choose the correct option:
- a
Statement I is false but Statement II is true
- b
Both Statement I and Statement II are true
- c
Both Statement I and Statement II are false
- d✓
Statement I is true but Statement II is false
Statement I is true but Statement II is false
Step 1 — Evaluate Statement I: For strong acid + weak base titration:
- Equivalence point pH < 7 (acidic)
- Methyl orange changes colour at pH 3.1–4.4 suitable for this titration ✓ Statement I is TRUE ✓
Step 2 — Evaluate Statement II: For weak acid (acetic acid) + strong base (NaOH) titration:
- Equivalence point pH > 7 (basic, ≈ 8.7)
- Phenolphthalein changes colour at pH 8.3–10 suitable for this titration
- Statement II says phenolphthalein is NOT suitable Statement II is FALSE ✗
Answer: Option (4) — Statement I true, Statement II false
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