12 grams of a mixture of sand and calcium carbonate on strong heating produced 7.6 grams of residue. How many grams of sand is present in the mixture?

Given, mass of mixture = 12 grams

Mass of residue = 7.6 grams

${CaCO}_3⟶CaO+{CO}_2$

 ${\mathrm{CO}}_2$ is evolved on the heating of mixture.

Mass of ${CO}_2=12–7.6=4.4grams$

According to the above reaction, 100 grams of ${CaCO}_3$ can evolve 44 grams of ${CO}_2$

mass of ${CaCO}_3$ that can evolve 4.4 grams of ${CO}_2$=10g

Mass of sand = 12 – 10 = 2 grams

Therefore, 2 grams of sand are present in the mixture.