Name the acid used for the preparation of hydrogen chloride gas in the laboratory. Why is this particular acid preferred to other acids?

(i) H₂SO₄ is used for the preparation of HCl gas in laboratory because it also acts as dehydrating agent.

Sulphuric acid is used for preparation of hydrogen chloride gas in laboratory. This is preferred over other acids because of the following reasons : 

(a) It has low volatility than HCl gas (so that the produced HCI gas is collected easily). 

(b) It has dehydrating properties, so the HCl gas produced can be effectively dehydrated to remove traces of water. 

(c) It has comparatively less oxidant power so formation of other by products can be avoided.