Question

The percent by mass of calcium in the compound calcium sulfate(CaSO4 ) is approximately
(1) 15% (3) 34%(2) 29% (4) 47%

Answer 1

We already know that the molar mass of Ca is 40.08 g/mol, of S is 32.07 g/mol, of O is 16 g/mol.

(40.08 g/mol)/ (40.08 g/mol+ 32.07 g/mol+ 4* 16 g/mol)* 100%= 29.44%

The correct answer is (2) 29%.

Hope this helps~