what happens to chloroform on warming with silver?

The correct answer is (2) Acetylene.

When chloroform is warmed with silver powder, it undergoes a reaction called the Carius reduction. In this reaction, the chlorine atoms in the chloroform are replaced by hydrogen atoms, forming acetylene.

The chemical equation for the reaction is:

 

Acetylene is a colorless, flammable gas with a garlic-like odor. It is used in a variety of applications, including welding, lighting, and the production of plastics.

The other options are incorrect. Option (1), Hexachloroethane, is a colorless, odorless liquid that is used as a solvent and fumigant. Option (3), Ethylene, is a colorless, odorless gas that is used in the production of plastics and other chemicals. Option (4), Carbon, is a black, non-metallic element that is the most abundant element on Earth.