We must fine the ratio of the molar masses between calcium carbonate and carbon dioxide. According to our chemical reaction above, we need 1 mole of calcium carbonate to produce 1 mole of carbon dioxide. The ratio between the two is 1:1. Now we find the molar masses using the periodic table to find the atomic mass of each element since the molar mass in the atomic mass in grams.
calcium carbonate= 42 grams + 12 grams + 3*16 grams = 102 grams/mole
carbon dioxide = 12 grams + 2*16 grams = 44 grams/mole
The reaction produces 0.22 grams of carbon dioxide. This represents (0.22/44) moles of carbon dioxide which is equivalent to .005 moles. This means that we need .005 moles of calcium carbonate to produce this.
.005 moles of calcium carbonate = (.005)(102 grams/mole) = .51 grams of calcium carbonate
Calcium on its own is 42 grams/mole, and .005 moles of calcium would equal .21 grams of calcium.
The percentage of calcium in the supplement would then be .21/1.998 = 10.5%
The closest answer would be E.