What does a molecular weight of 18 g/mol for water correspond to in atomic weights of its elements?

A molecular weight of 18 g/mol for water can be understood by examining the atomic weights of its constituent elements: hydrogen (H) and oxygen (O). The molecular formula of water is H₂O, indicating that each molecule contains two hydrogen atoms and one oxygen atom.

The atomic weight of hydrogen is approximately 1 g/mol. Therefore, for two hydrogen atoms, the total weight contributed by hydrogen is:

2 H × 1 g/mol = 2 g/mol.

The atomic weight of oxygen is about 16 g/mol. Since there is one oxygen atom in a water molecule, the total weight from oxygen is:

1 O × 16 g/mol = 16 g/mol.

When you add these two contributions together, the total molecular weight of water is:

2 g (from H) + 16 g (from O) = 18 g/mol.

This confirms that the contribution of 2 g from hydrogen and 16 g from oxygen accurately represents the molecular weight of water. Therefore, the correct corresponding atomic weights of its elements reflect how the composition of water leads to its overall molecular weight of 18 g/mol.

Other options suggest incorrect distributions or amounts that do not match the known atomic weights of the elements involved in the composition