Apparatus: Two test tubes, bent tube, rubber cork, burner, etc.
Chemicals: Calcium carbonate, freshly prepared lime water.
Procedure: Take some calcium carbonate in a test tube. Fit a bent tube to this test tube with the help of a rubber cork. Insert the other end of the bent tube in the freshly prepared lime water taken in the other test tube. Heat the powdered calcium carbonate in the first test tube strongly.
What will you observe?

Explanation

In the second test tube, the lime water turns milky and in the first test tube, white powder remains behind. Calcium carbonate undergoes decomposition to form calcium oxide, the white powder and carbon dioxide gas, which turns lime water milky.
`underset("carbonate")underset("Calcium")(CaCO_(3(s)))overset(Delta)rarrunderset("oxide")underset("Calcium")(CaO_((s)))+underset("dioxide")underset("Carbon")(CO_(2)uarr`Inference: In this reaction, calcium carbonate decomposes into two products, CaO and `CO_(2)`. Hence, this is a decomposition reaction. [Note: Students are expected to refer the accompanying QR code for demonstration of the activity.]