We have the next molecule: Ca(OCl)2
To start, we will calculate the molar mass of this compound,
The molar mass Ca(OCl)2 = 1 x 40.07 Ca + 2 x 16.00 O + 2 x 35.45 Cl = 142.97 g/mol
Furthermore, we have 2 atoms of Cl in this molecule, so its mass in it will be 2 x 35.45, equal to 70.9 g/mol.
So, % by mass = (70.9 g Cl2/142.97 g Ca(OCl)2) x 100 = 49.59 %
Answer: 49.59 % by mass
