Empirical Formula: a formula giving the proportions of the elements present in a compound but not the actual numbers or arrangement of atoms.
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A) We call Group 1:
C3H6O3 => simplifying: CH2O
B) C4H4O2 => simplifying: C2H2O
Its empirical formula is different from A, so we call it Group 2.
C) C2H2O2 =>simplifying: CHO
It is different from the 2 before. We call it Group 3.
D) C5H10O5 => simplifying: CH2O
Look at A, these two have the same empirical formula. We put D in Group 1
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First, I changed the developed formulas into molecular formulas, then I simplified the subindexes and I got the empirical formulas. After that, I compared every empirical formula.