Answer:
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I believe the answer would be b
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.
First, let's count mole of 10 g Calcium Carbonate
mole = Mass / Molecular Mass
Calcium Carbonate = CaCO₃
Molecular Mass = Ar Ca + Ar C + (3 x Ar O)
Molecular Mass = 40 + 12 + (3 x 16)
Molecular Mass = 100
next
Mole of CaCO₃ = 10 gram / 100
Mole of CaCO₃ = 0,1 mol
then equal the reaction equation first
CaCO₃ + 2 HCl ==> CaCl₂ + CO₂ + H₂O (Equal)
To count the mass of carbon dioxide that produced we must know the mole of CO₂ first
we can count by coefficient comparison
mole CO₂ =
x mole CaCO₃
mole CO₂ = (1/1) x 0,1 mole
mole CO₂ = 0,1 mole
so
Mass of CO₂ = mole CO₂ x Molecular Mass of CO₂
Mass of CO₂ = 0,1 mole x (12 + (2 x 16))
Mass of CO₂ = 0,1 mole x 44
Mass of CO₂ = 4,4 g
so, mass of carbon dioxide that's produced by 10 g of calcium carbonate on reaction with chloride acid is 4,4 g.