Carbon dioxide is one of the main causes of global warming.

This factory is emitting a large amount of sulfur dioxide.

He ate one apple.

He is majoring in chemistry at university.

This chemical reacts when heat is added.

This chemical reaction is very dangerous.

Basic oxides react with acids to produce salt and water.

Nitrous oxide is one cause of air pollution.

I made a mistake.

His fault is unforgivable.