________ gas is used for the manufacturing of bleaching powder.

Chlorine

The correct answer is option 4. Chlorine.

The gas used for the manufacturing of bleaching powder is Chlorine

Here's why:

Bleaching powder, also known as calcium hypochlorite (Ca(OCl)₂), is a chemical compound used as a bleaching agent, disinfectant, and deodorizer.

It is manufactured by treating slaked lime (calcium hydroxide, Ca(OH)₂) with chlorine gas (Cl₂) in a controlled reaction.

During this process, the chlorine reacts with the calcium hydroxide, resulting in the formation of calcium hypochlorite, the primary component of bleaching powder.

Therefore, chlorine gas is the essential element for producing bleaching powder.