1)Water boils at 100°C at 1 atm pressure.
2)Water can be separated into other substances by a chemical process.
3)Water is a compound.
4)Water and salt have different boiling points.
5)Water is 11% hydrogen and 89% oxygen by mass.
I think its # 5, because no matter which mass water has, the composition will always be 11% hydrogen and 89% oxygen
5 regardless of the source, water is always 11% H and 89% O