Answer:
D. the mass of one mole of a substance
Explanation:
The molar mass of a substance is the mass in grams of one mole of the substance.
- For an element, the molar mass is the relative atoms mass expressed in grams.
- For example 23g of Na, 40g of oxygen
- For compounds, molar mass is the gram -formula or gram - molecular weight.
- This is determined by the addition of its component atomic masses and then expressed in grams.
