Question

The lime water turns milky when X gas is passed through it. This milkiness is caused due to the formation of Y. Identify X and Y from the options given below.

• A. X- $\text{CO}$, Y- ${\text{CaCO}}_3$
• B. X- ${\text{CO}}_2$, Y- ${\text{Ca(OH)}}_2$
• C. X- ${\text{CO}}_2$, Y- ${\text{CaCO}}_3$
• D. X- ${\text{O}}_2$, Y- ${\text{Na}}_2{\text{CO}}_3$

Answer 1

The correct option is C X- ${\text{CO}}_2$, Y- ${\text{CaCO}}_3$

The lime water (calcium hydroxide) turns milky when carbon dioxide gas (${\text{CO}}_2$) is passed through it. This is due to the formation of a white insoluble precipitate of calcium carbonate (${\text{CaCO}}_3$), which is also known as limestone. The reaction involved is:

${\text{Ca(OH)}}_2\text{(aq)}+{\text{CO}}_2\text{(g)}\to {\text{CaCO}}_3\text{(s)}+{\text{H}}_2\text{O(l)}$

Thus, ${\text{X- CO}}_2,{\text{Y- CaCO}}_3$.