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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3mc201

of Fe and of S are heated to form FeS, and the cooled product (with any leftover reactant) is treated with excess dilute HCl: and . Use Fe = 56, S = 32 and 22.4 L/mol at STP. Select the correct statement(s).

  1. A of FeS is formed.
  2. BThe total volume of gas evolved with HCl is at STP.
  3. CS is the limiting reagent in the heating step.
  4. DThe volume of evolved is at STP.

Answer: B, C, D

n(Fe) = 0.25 mol, n(S) = 0.20 mol, so S is limiting and FeS = 0.200 mol x 88 = 17.6 g (not 22.0 g). Leftover Fe = 0.050 mol. Gas evolved = H2S 0.200 mol + H2 0.050 mol = 0.250 mol = 5.6 L, and H2S alone = 4.48 L.
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