CGPET 2021 Solved Paper

First we need to find empirical formula.

∴ C:H:O=1:1:2
Hence, empirical formula is CHO2.
Molecular mass of diethyl ether is (C2H5OC2H5) 2×73=146u
∴ Formula mass of ethyl group =29u
In diethyl ether two ethyl group must have replaced the H-atom of dibasic acid.
∴ The molecular mass of acid = Molecular mass of diethyl ether −(2× mass of ethyl group )+ mass of hydrogen
=149−(2×29)+2=90u
∴ Molecular formula of acid
=

Molecular‌mass‌of‌acid

Empiricial‌mass‌formula

×CHO2
=

90

(12+1+16×2)

×CHO2
=

90

45

×CHO2=2×CHO2
∴ Molecular formula of acid =C2H2O4