Acetic acid was added to a solid X kept in a test tube. A colourless and odourless gas was evolved. The gas was passed through lime water which turned milky. It was concluded that.
A. Solid X is sodium hydroxide and the gas evolved is CO₂,

B. Solid X is sodium bicarbonate and the gas evolved is CO₂

C. Solid X is sodium acetate and the gas evolved is CO₂

D. Solid X is sodium chloride and the gas evolved is CO₂

When any acid reacts with metal hydrogencarbonate, the products formed are salt, carbon dioxide (CO₂) and water.

Metal hydrogencarbonate + Acid → Salt + Carbon dioxide + Water

Hence, when acetic acid reacts with sodium bicarbonate (NaHCO₃), a colourless and odourless of carbon dioxide gas is evolved.

When carbon dioxide gas is passed through lime water [(CaOH)₂], the following reaction takes place:

i. In this reaction, when limewater comes in contact with the gas

released in the form of an effervescence, it turns milky. This is a

chemical test for carbon dioxide gas.

ii. When limewater turns milky, it is confirmed that the

effervescence is of carbon dioxide.