Q. 20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample ? (At. Wt. : Mg = 24)
A) 60
B) 84
C) 75
D) 96
Explanation
[Solution] 20 g pure $MgCO_3$ (0.238 mol) would give 9.52 g MgO; actual 8 g, so purity = 8/9.52 × 100 = 84%. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.