Question

Heating a limestone at around ${1000}^{\circ }C$ leads to a chemical reaction. This can be most easily confirmed by

• A. looking at the color change of the solid
• B. smelling the gas evolved
• C. watching the color of the gas evolve
• D. none of the above

Answer 1

The correct option is D

none of the above

1. When limestone i.e., Calcium carbonate $\left(CaC{O}_3\right)$ is strongly heated at ${1000}^{\circ }C$ it decomposes into Calcium oxide $\left(CaO\right)$ and Carbon dioxide $\left(C{O}_2\right)$.
2. The reaction would be, $\underset{(Calciumcarbonate)}{\underbrace{CaC{O}_3\left(s\right)}}\stackrel{{1000}^{\circ }C}{\to }\underset{(Calciumoxide)}{\underbrace{CaO\left(s\right)}}+\underset{(Caobondioxide)}{\underbrace{C{O}_2\left(g\right)\uparrow }}$
3. Calcium oxide $\left(CaO\right)$ is also white in color as Calcium carbonate $\left(CaC{O}_3\right)$, so no change in color could be experienced here. hence option (A) is incorrect.
4. The gas evolved here is carbon dioxide $\left(C{O}_2\right)$ is a odorless gas, hence options (B) is incorrect.
5. The gas evolved here is carbon dioxide $\left(C{O}_2\right)$ is a colourless gas, hence options (C) is incorrect.

Hence the correct option would be D) None of these,