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1 g of an impure sample of magnesium carbonate (containing no thermally decomposable impurities) on complete thermal decomposition gave 0 . 44   g of carbon dioxide gas. The percentage of impurity in the sample is

Options

  1. A0 %
  2. B4 . 4 %
  3. C16 %
  4. D8 . 4 %

Correct answer

C. 16 %

Step-by-step solution

Consider, MgCO 3   → MgO   +   CO 2 ↑ MgCO 3 : 1 × 24 + 1 × 12 + 3 × 16 = 84   g CO 2 : 1 × 12 + 2 × 16 = 44   g 100 % pure 84   g MgCO 3 on heating gives 44   g CO 2 Given that 1   g of MgCO 3 on heating gives 0 . 44   g CO 2 Therefore, 84   g MgCO 3 sample on heating gives 36 . 96   g CO 2 Percentage of purity of the sample = 36 . 96   g   of   CO 2 44   g   of   CO 2 ×   100  

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