Match each element or compound with the appropriate symbol or molecular formula

Carbon — C

Oxygen — O

Carbon dioxide — CO2

Water — H2O

Hydrogen — H

Well to my expert knowledge and my exquisite calculations i think the the negative ion # 412 is the key to sucess

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