He walked on the moon wearing a space suit.

I am interested in space exploration.

He is majoring in aerospace engineering.

Radioactive elements are produced in nature and scientific experiments.

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.

Cosmic background radiation is considered evidence of the Big Bang.