If 1.4 g of calcium oxide is formed by the complete decomposition of calcium carbonate, then the amount of calcium carbonate taken and the amount of carbon dioxide formed will be respectively :(a) 2.2 g and 1.1 g (b) 1.1 g and 2.5 g (c) 2.5 g and 1.1 g (d) 5.0 g and 1.1 g

Correct Answer: (c) 2.5 g and 1.1 g   

Explanation: Molecular mass of CaCO₃: 40 + 12 + (16 × 3) = 100g

Molecular mass of CaO: 40 + 16 = 56g

Molecular mass of CO₂: 12 + (16 × 2) = 44g

The reaction for the decomposition of calcium carbonate:

$CaCO_3 → CaO + CO_2$

100g             56g     44g

X                   1.4g      Y

56 g of CaO is obtained when 100g of CaCO₃ is burnt.

Therefore, to get 1.4g of CaO, the amount of CaCO₃ to be burnt will be

100×1.456=2.5g

For CO₂,

100g of CaCO₃ yields 44g of CO₂

Therefore, 2.5g of CaCO₃ will yield;

(44×2.5)/100

=1.1 g

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Updated on: 10-Oct-2022

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