NTA Abhyas JEE Main2020ChemistrySome Basic Concepts of ChemistryPractice

10 g of M g C O 3 decomposes on heating to 0.1 mole C O 2 and 4 g M g O . The percent purity of M g C O 3 is (Given that atomic weights of Mg, C and O are 24, 12 and 16 u)

Options

A44 %
B54 %
C74 %
D84 %

Correct answer

D. 84 %

Step-by-step solution

M g C O 3 decomposes as below: M g C O 3 → M g O + C O 2 mole ratio = 1 : 1 : 1 Thus 0.1 mole of C O 2 will be produced by 0.1 mole of M g C O 3 . Mass of M g C O 3 in 10 g sample = 0.1 × 84 = 8.4 g Percent purity = 8.4 10 × 100 = 84 %

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