Q. $x$ grams of calcium carbonate was completely burnt in air. The weight of the solid residue formed is 28 g. What is the value of $x$ (in grams)?
A) 44
B) 200
C) 150
D) 50
Explanation
(d)
$CaCO_{3}\ (s)\overset{\ \ \mathrm{\Delta}\ \ \ }{\rightarrow}CaO(s) + CO_{2}\ (g)$
100 g 56 g
$\therefore$ 56 g CaO is obtained from=100g $CaCO_{3}$
$\therefore$ 28 g CaO is obtained from=$\frac{100 \times 28}{56}$
=50 g $CaCO_{3}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.