A day has 24 hours.

Organic solvents play an important role in chemical reactions.

He ate one apple.

Calcium carbide is a major raw material for acetylene gas.

It is important for each person to fulfill their role.

He was involved in the development of the hydrogen bomb.

Hydrogen sulphide is extremely toxic, and particularly at high concentrations, it is lethal to humans.

This compound is stabilized by hydrogenation.

He hydrogenated fatty acids in a chemical experiment.

He acted according to my instructions one by one.