Q4 / 54 · JEE Advanced 2022 (Paper 1) · Chemistry

The treatment of an aqueous solution of 3.74 g of CuNO32 with excess KI results in a brown solution along with the formation of a precipitate. Passing H2S through this brown solution gives another precipitate X. The amount of X (in g) is____[Given: Atomic mass of H=1, N=14, O=16, S=32, K=39, Cu=63, I=127]

Correct answer: 0.32

Solution

Number of moles of CuNO32=3.74187=0.02

2CuNO32+4KI→Cu2I2↓+I2+4KNO3

Number of moles of Cu2l2 precipitated =0.01

I2brown solution+H2S→S↓+2HI

Number of moles of S precipitated =0.01

Mass of S precipitates =0.01×32g=0.32 g

Hence, the correct answer is 0.32.

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