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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 ?
Some Basic Concepts of Chemistry
Solution:
$\underset{\text{1 mol}}{CaCO _3} \xrightarrow{\Delta}\underset{\text{1 mol }}{ CaO }+ CO _2$
$=100\,g =40+16$
$=56\,g$
To produce $56\, g$ of residue $(CaO)$, $CaCO_{3}$ needed
$=100\,g$
$\therefore $ To produce $28\, g $ of residue, $CaCO_{3}$ needed
$=\frac{100}{56}\times28$
$=50\,g$