What we can actually do is to find the number of moles of Ca.
moles Ca = 0.72 g / (40.08 g/mol) = 0.018 mol
From the given choices, we can all see that there are 1 mol of compound
per 1 mole of Ca. Therefore the actual moles of compound is also 0.018 mol.
From this, calculate the mass and the answer is the one which will give 2 g.
