Question 6
The formula mass of calcium carbonate is 100. What is its molar mass?
The right answer is the one marked above.
100 g mol-1. The number is the same as the formula mass; what changes is that a unit is added.
Writing "100" with no unit is the answer for the formula mass. "100 g" is wrong too — it is a mass per mole, so the mol-1 part of the unit is essential.