Exactly 50 meq of acidified $KMnO X_{4}$ ( $100 mL$ of $0.1 M$ , reduced to $Mn X^{2 +}$ ) is available. Which of the following reductants would be oxidised exactly completely by it? ( $FeSO X_{4}$ to $Fe X^{3 +}$ ; $H X_{2} C X_{2} O X_{4}$ to $CO X_{2}$ ; $H X_{2} O X_{2}$ to $O X_{2}$ ; $Na X_{2} SO X_{3}$ to $Na X_{2} SO X_{4}$ .)

Answer: A, B, C

Required meq

= 50

. A:

100 \times 0.5 \times 1 = 50

(match). B:

50 \times 0.5 \times 2 = 50

(match). C:

50 \times 0.5 \times 2 = 50

(match). D:

25 \times 0.5 \times 2 = 25

(not enough).