Answer: 2H2O
Step-by-step explanation:
Water is made up of Hydrogen and Oxygen. The symbol of Hydrogen is H but it cannot exist as monoatomic gas when combined with oxygen but diatomic therefore it is represented as H2. The symbol of Oxygen is O.
Combining both will give us the chemical symbol of water which is H2O(which is just one molecule of water)
2 molecules of water will then give us 2H2O.