Let us suppose that we have 1 mol of FeCr2O4. I'm going to use approximate masses because I have no idea what your periodic table will say. Just put in the exact masses from your periodic table.
Fe = 56
Cr*2 = 2*52 = 104
O4 = 4*16 = 64
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Total = 56 + 104 + 64 = 224
The % oxygen = (64 / 224) * 100 = 28.5 % but none of your answers match this. Perhaps you are talking about Fe2(Cr2O4)3 The brackets make all the difference in the world.
Without going through all the detail I did before, The molecular mass is
Fe * 2 = 112
Cr * 6 = 312
O * 12 = 192
The total molecular mass = 616
The % Oxygen = (192 / 616) * 100 = 31% roughly. That answer isn't there either.
Let's wait and see who else answers.
if da ceiling in a square that means it has four sides. If each side is 39 feet and there are four sides you would multiply 39 times 4 which equals 156. If one can of paint can cover 169 ft.² and the ceiling is only 156 ft.² then you would only need 1 CAN OF PAINT.
Y=15 x=60
•1/3 •1/3
y=5 x=45
When a cell uses chemical energy to perform work it couples exergonic reaction with endergonic reaction.
