What is the molar mass of cortisone?

Question

a molecule of cortisone contains 21 atoms of carbon along with otehr atoms. The mass percentage of carbon in cortisone is 69.8%.

A) 175.6 g/mol
B) 252.2 g/mol
C) 287.6 g/mol
D) 312.8 g/mol
E) 360.4 g/mol

Answer 1

You have 21*12 = 252 g/mol coming from C.
That is the 69.8% of the total mass, so MW=252/0.698=361.0 g/mol

Thus the correct answer is E