Question:
10 g of MgCO$_3$ decomposes on heating to 0.1 mole CO$_2$ and 4 g MgO. The percent purity of MgCO$_3$ is
10 g of MgCO$_3$ decomposes on heating to 0.1 mole CO$_2$ and 4 g MgO. The percent purity of MgCO$_3$ is
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Use mole ratio to find actual reacting mass.
Updated On: May 1, 2026
- 24 %
- 44 %
- 54 %
- 74 %
- 84 %
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The Correct Option is D
Solution and Explanation
Concept:
Decomposition: \[ \text{MgCO}_3 \rightarrow \text{MgO} + \text{CO}_2 \] Mole ratio = 1:1.
Step 1: Given CO$_2$ formed.
\[ 0.1\ \text{mol CO}_2 \Rightarrow 0.1\ \text{mol MgCO}_3 \]
Step 2: Mass of pure MgCO$_3$.
Molar mass = 84 g/mol \[ \text{Mass} = 0.1 \times 84 = 8.4\ \text{g} \]
Step 3: Percent purity.
\[ \frac{8.4}{10} \times 100 = 84\% \]
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