Write your observation and a balanced equation for Zinc carbonate being heated.

On strong heating, light amorphous white solid changes to pale yellow. Carbon dioxide gas is given off which turns lime water milky.

The residue, on cooling, changes to a white colour. i.e., residue is yellow when hot and white when cold.

$\begin{matrix} \text{ZnCO}$3 &\xrightarrow\Delta & \text{ZnO} & + & \text{CO}2\uparrow \ \text{[Zinc} & & \text{[Zinc oxide]} & & \text{[Carbon} \ \text{carbonate]} & & \text{[yellow - hot]} & & \text{dioxide]} \ \text{[white]} & & \text{[white - cold]} \end{matrix}