Excellent! Because water is made up of $$2$$ H atoms and $$1$$ O atom, the mass of 1 molecule of water is $$\left(2 \times 1\right) + \left(16 \times 1\right) = 18 \, \mathrm{amu}$$
• $$2 \, \mathrm{amu}$$ of Hydrogen and $$16 \, \mathrm{amu}$$ of Oxygen
• $$1 \, \mathrm{amu}$$ of Hydrogen and $$16 \, \mathrm{amu}$$ of Oxygen
• $$2 \, \mathrm{amu}$$ of Hydrogen and $$8 \, \mathrm{amu}$$ of Oxygen
• $$2 \, \mathrm{amu}$$ of Hydrogen and $$1 \, \mathrm{amu}$$ of Oxygen