Question

A metal carbonate $X$ on reacting with an acid gives a gas which when passed through a solution $Y$ gives the carbonate back. On the other hand, a gas $G$ that is obtained at the anode during electrolysis of brine is passed on dry $Y$, it gives a compound $Z$, used for disinfecting drinking water. Identity $X,Y,G$ and $Z$.

• A. $X\to \text{Hydrogen bicarbonate};Y\to \text{Lime water};G\to \text{Chlorine gas};Z\to \text{Calcium carbonate}$
  
• B. $X\to \text{Calcium oxychloride};Y\to \text{Lime water};G\to \text{Chlorine gas};Z\to \text{Calcium carbonate}$
  
• C. $X\to \text{Calcium carbonate};Y\to \text{Calcium oxychloride};G\to \text{Chlorine gas};Z\to \text{Limewater}$
  
• D. $X\to \text{Calcium carbonate};Y\to \text{lime water};G\to \text{Chlorine gas};Z\to \text{Calcium oxychloride}$
  

Answer 1

The correct option is D $X\to \text{Calcium carbonate};Y\to \text{lime water};G\to \text{Chlorine gas};Z\to \text{Calcium oxychloride}$

Calcium carbonate gives carbon dioxide gas when reacts with hydrochloric acid.
$CaC{O}_3+2HCl⟶CaC{l}_2+C{O}_2+H_{2}O$

Carbon dioxide turns lime water milky when passed through it because of formation of calcium carbonate.

When carbon dioxide; so formed; is passed through lime water, lime water turns milky because of the formation of calcium carbonate.

$Ca(OH{)}_2+C{O}_2\to CaC{O}_3+H_{2}O$

On the electrolysis of brine, chlorine gas is deposited over anode which gives calcium oxychloride (Bleaching powder) on passing over slaked lime. The bleaching powder is used in disinfecting the drinking water.

$Ca(OH{)}_2+C{l}_2⟶CaOC{l}_2+H_{2}O$

Bleaching powder is used for disinfecting drinking water.

Therefore, metal carbonate ${}^{\prime }{X}^{\prime }$ is calcium carbonate.

• Solution $Y$ is lime water (Calcium hydroxide).
• Gas $G$ is chlorine gas.
• Dry $Y$ is dry calcium hydroxide (dry slaked lime).
• Compound $Z$ is bleaching powder (Calcium oxychloride).