Step 1
Atomic masses per mole of each element are needed to solve this question:
Let's look them up, please
For C) 12.01 g/mol
For H) 1.008 g/mol
For O) 15.99 g/mol
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Step 2
The compound provided: C3H7O
Its molar mass = 3 x 12.01 g/mol (C) + 7 x 1.008 g/mol (H) + 15.99 g/mol (O)
The molar mass = 59.079 g/mol
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Step 3
Each % will be calculated as:
C) (3 x 12.01 g/mol C/59.079 g/mol) x 100 = 61 % approx.
H) (7 x 1.007 g/mol H/59.079 g/mol) x 100 = 12 % approx.
O) 100 % - 61 % -12 % = 27 %
(For O, the same procedure can be made too)
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Answer:
Composition:
61 % C
12 % H
27 % O