Question

13. Assertion (A): If excess of carbon dioxide is passed through lime water, it becomes transparent.

Reason (R): Calcium bicarbonate is soluble in water.

• A. Both (A) and (R.) are true and (R) is the correct explanation for (A).
• B. Both (A) and (R) are true but (R) is not the correct explanation for (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Answer 1

The correct option is A

Both (A) and (R.) are true and (R) is the correct explanation for (A).

Explanation for Assertion statement:

• When Carbon dioxide $\left({\mathrm{CO}}_2\right)$ is passed through Lime water or Calcium hydroxide$\left[\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\right]$, it turns milky and Calcium carbonate $\left({\mathrm{CaCO}}_3\right)$ is formed.
• The reaction involved is:

$\underset{\mathrm{Lime}\mathrm{water}}{\mathrm{Ca}{\left(\mathrm{OH}\right)}_2}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2}\to \underset{\mathrm{Calcium}\mathrm{carbonate}\left(\mathrm{milkiness}\right)}{{\mathrm{CaCO}}_3}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}}$

• Now, when excess Carbon dioxide is passed, the milky appearance disappears and becomes transparent due to the formation of Calcium bicarbonate$\left[\mathrm{Ca}{\left({\mathrm{HCO}}_3\right)}_2\right]$.
• The reaction involved is: ${\mathrm{CaCO}}_3+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2\to \mathrm{Ca}{\left({\mathrm{HCO}}_3\right)}_2$

Explanation for Reason statement:

• Calcium bicarbonate formed which is colorless and soluble in water.

Hence, option (A) is the correct answer. Both (A) and (R.) are true and (R) is the correct explanation for (A).