20.0 mL of 0.0200 M $KMnO X_{4}$ in acidic medium is completely used up (no excess of either reagent) by which of the following? (H = 1, C = 12, O = 16, S = 32, Fe = 56; complete oxidation of the named species, $Fe X^{2 +}$ to $Fe X^{3 +}$ , oxalate to $CO X_{2}$ , $H X_{2} O X_{2}$ to $O X_{2}$ )

Answer: A, B, C

The permanganate supplies

20.0 \times 0.0200 \times 5 = 2.00

meq.

FeSO X_{4}

: 2.00 mmol x 1 = 2.00 meq. Oxalic acid dihydrate: 1.00 mmol x 2 = 2.00 meq.

H X_{2} O X_{2}

: 1.00 mmol x 2 = 2.00 meq.

FeC X_{2} O X_{4}

: 1.00 mmol x 3 = 3.00 meq, which is too much. So A, B and C are correct.