[poll id=”148″]
ANSWER: E. 28.6%
This is a general chemistry problem that is almost ASSUMED to be seen on the OAT, in one way or another. One simply utilizes the periodic table (provided in the exam) and adds up the entire molecular weight of FeCr2O4.
Fe = 55.8
Cr = 52 (x2)
O = 16 (x4)
Total molecular weight: ~223.85
Divide the oxygen species by this: (16×4)/(223.85) = .286
Multiply by a 100 to get the percentage form: .286 x 100 = 28.6 %