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Empirical and molecular formula, percentage composition
JEE Main level
Numerical answer
Difficulty 2 of 3
mc171
Calculate the mass of iron, in grams, present in
1.00
kg
of pure
Fe
X
3
O
X
4
(Fe = 56, O = 16). Give the answer to the nearest integer.
Numerical answer type, answer in g, tolerance 0.5.
Answer: 724 g
Molar mass of Fe3O4 = 168 + 64 = 232 g/mol. Mass fraction of Fe = 168/232 = 0.7241. Iron in 1000 g = 724.14 g, i.e. 724 g to the nearest integer.
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