On heating, potassium permanganate decomposes as 2KMnO4 -> K2MnO4 + MnO2 + O2. A 31.6 g sample of KMnO4 is decomposed completely (K = 39, Mn = 55, O = 16; 22.4 L mol^-1 at STP). Which of the following statements is/are correct?

The volume of O2 liberated at STP is 2.24 L.

The residue contains 8.7 g of MnO2.

The mass of the solid residue is 28.4 g.

The volume of O2 liberated at STP is 2.24 L.

The residue contains 8.7 g of MnO2.

The mass of the solid residue is 28.4 g.

K2MnO4 makes up 50.0% of the residue by mass.

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3mc055

On heating, potassium permanganate decomposes as $2 KMnO X_{4} K X_{2} MnO X_{4} + MnO X_{2} + O X_{2}$ . A $31.6 g$ sample of $KMnO X_{4}$ is decomposed completely (K = 39, Mn = 55, O = 16; $22.4 L mo l^{- 1}$ at STP). Which of the following statements is/are correct?

n (KMnO X_{4}) = 31.6/158 = 0.20

mol, giving 0.10 mol

O X_{2}

(

2.24

3.2

g). Residue

= 31.6 - 3.2 = 28.4

g. It contains 0.10 mol each of

K X_{2} MnO X_{4}

(

197

g/mol,

19.7

g) and

MnO X_{2}

(

87

g/mol,

8.7

g). Mass fraction of

K X_{2} MnO X_{4}

= 19.7/28.4 = 69.4%

, not

50%