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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3mc158

10.0 g of a brass sample (Zn + Cu) is treated with excess dilute HCl and 1.12 L of at STP is evolved; copper does not react (; ; 22.4 L/mol). Which statements are correct?

  1. A0.05 mol of HCl is consumed
  2. BThe alloy contains 32.5% zinc by mass
  3. C0.10 mol of HCl is consumed
  4. DThe mass of copper in the sample is 6.75 g

Answer: B, C, D

Moles of = 1.12/22.4 = 0.05 = moles of Zn, so Zn mass = 3.25 g = 32.5% and Cu = 6.75 g. HCl consumed = 2 x 0.05 = 0.10 mol, so 0.10 is true and 0.05 is false.
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