Final answer:
To find the molar mass of water (H₂O), multiply the atomic mass of hydrogen (1.008 g.mol⁻¹) by 2 and add the atomic mass of oxygen (15.999 g.mol⁻¹) to get 18.015 g.mol⁻¹.
Step-by-step explanation:
To find the molar mass of water (H₂O), you would follow option (a): Multiply the relative atomic mass of hydrogen by 2 and add to the relative atomic mass of oxygen. The step-by-step process involves taking the atomic masses of hydrogen and oxygen from the periodic table, multiplying them by their respective number of atoms in a water molecule, and then summing these values.
So to calculate the molar mass of water, we use the relative atomic masses: hydrogen (1.008 g.mol⁻¹) and oxygen (15.999 g.mol⁻¹). The calculation is 2x1.008 g.mol⁻¹ H + 15.999 g.mol⁻¹ O = 18.015 g.mol⁻¹ H₂O.
It's essential to understand that the molar mass represents the mass of one mole of a substance, typically measured in grams per mole (g/mol).