Assertion: Calcium carbonate when heated gives calcium oxide and water.
Reason: On heating calcium carbonate decomposition reaction takes place.

Dear student,
Option D is correct.
$$\begin{gathered} Assertion : Calcium carbonate when heated gives calcium oxide and water. \\ This is false , because on heating calcium carbonate calcium oxide and carbon dioxide are formed. \\ CaC{O}_3--{-}^{∆}---> CaO + C{O}_2 \\ Reason :On heating calcium carbonate decomposition reaction takes place. \\ This is also true. \\ Assertion is false and Reason is true. \end{gathered}$$


Hope this information will clear your doubts about topic.

If you have any more doubts just ask here on the forum and our experts will try to help you out as soon as possible.

Regards