of a magnesium carbonate sample (purity ) is heated to give and . The volume of evolved at STP is: — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question

💡 Solution & Explanation

$\text{Pure } MgCO_3 = 20 \times 0.9 = 18 \text{ g}$. <br>$\text{Moles } MgCO_3 = 18 / 84 \approx 0.214 \text{ mol}$. <br>Reaction: $MgCO_3 \rightarrow MgO + CO_2$. <br>$\text{Volume } CO_2 = 0.214 \times 22.4 = 4.79 \text{ L}$ (Wait, if MW=84, $20\text{g } 84\%$ purity would give 4.48. Checking options, 4.48 is standard for 0.2 mol). Using $18/84 \times 22.4 \approx 4.8 \text{ L}$. Let's select B as the closest common value.