commercial scuba divers use tanks filled with a mixture of gases known as trimix on very long, deep dives. Trimix is composed of 70 percent nitrogen, 10 percent oxygen, and 20 percent helium. The total pressure of trimix inside a certain tank at the beginning of a dive is 118.4atm.

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom