Question

The mass of CaO that would be obtained by heating 20 kg of $90\%$ pure lime stone is:

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

Mass of pure limestone = $\left(\frac{90}{100}\right)\times 20=18kg$
$CaC{O}_3\stackrel{\Delta }{\to }CaO+C{O}_2$
100 kg of $CaC{O}_3$ forms 56 kg of CaO
18 kg of $CaC{O}_3$ forms $\frac{(18\times 56)}{100}=10.08\text{kg of CaO}$