Identify the incorrect statement(s) among the following regarding redox reactions in acidic medium:

1 mol of MnO4⁻ can oxidize 5 mol of Fe²+ in acidic medium
1 mol of Cr2O7²- can oxidize 6 mol of Fe²+ in acidic medium
2 mol of Cu2S can be oxidized by 2.6 mol of MnO4⁻ in acidic medium (Cu2S -> Cu²+ + SO2)
2 mol of Cu2S can be oxidized by 8/3 mol of Cr2O7²- in acidic medium (Cu2S -> Cu²+ + SO2)

Correct answer: 1 mol of MnO4⁻ can oxidize 5 mol of Fe²+ in acidic medium

Solution

MnO4⁻ gains 5e⁻ per mole, so 1 mol MnO4⁻ oxidizes 5 mol Fe²+ (each loses 1e⁻). The option stating 10 mol is incorrect. Cr2O7²- gains 6e⁻ per mole, so 1 mol oxidizes 6 mol Fe²+, not 12. For Cu2S with n-factor 8: 2 mol Cu2S needs 16 equivalents; 2.6 mol MnO4⁻ gives 13 eq (insufficient), and 8/3 mol Cr2O7²- gives 16 eq (correct).

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