Question

Name the following:

Two sources of occurrence of carbon dioxide.

Answer 1

• Carbon dioxide is present on earth in the free state and in the combined state.
• In the free state, about 0.03% to 0.04% by volume of carbon dioxide is present in the atmosphere or the earth.
• In the combined state, it occurs as metal carbonates and bicarbonates in the earth's crust in the form of limestone$\left({\mathrm{CaCO}}_3\right)$ and dolomite$({\mathrm{MgCO}}_3·{\mathrm{CaCO}}_3)$.