Using punctuation marks correctly is important for understanding sentences.

What is this solid made of?

There are sediments at the bottom of this lake that have accumulated over centuries.

Lithium hydride plays an important role in chemical reactions.

Hydrogen peroxide is often used for disinfecting wounds.

Tritium is one of the radioactive isotopes.

Arsine is a colorless, odorless, and highly toxic gas.

The pH of this liquid is 7.

He is receiving countless blessings.

The indefinite article is a basic part of English grammar.