Answer: The number of moles of calcium carbonate is 0.637 moles
Step-by-step explanation:
To calculate the number of moles, we use the equation:

We are given:
Given mass of calcium carbonate = 63.8 g
Molar mass of calcium carbonate = 100.09 g/mol
Putting values in above equation, we get:

Hence, the number of moles of calcium carbonate is 0.637 moles