Q51 IMAT 2019 Isomers

Practice Question Solving
1

Which of the following pairs of structural formulae represent structural isomers?

1 CH3CH2OH and CH3OCH3
2 CH3CH(CH3)CH2CH2CH3 and CH3CH2CH2CH(CH3)CH3
3 CH(OH)=CHCH2OH and CH3CH2COOH

A.2 only
B.1 only
C.1, 2 and 3
D.1 and 3 only
E.2 and 3 only

Can anyone explain to me why option 2 aren’t isomers? The methyl group is on different carbons so the same formula but different arrangement. I’d say the first is 2-methyl pentane and the other 1-methyl pentane. Correct answer is D

2

Both of them are the same ie 2 Methyl Pentane.

Write skeletal formula for both the structures and you’ll find that the longest chain in both cases is 5C alkane with methyl attached to second carbon.

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3

@AriHoresh
Question Shouldn’t answer be A instead of D
Shouldn’t 1 and 3 be functional group isomers while 2 be structural isomer as the q asks only structural isomer,Please guide

5

functional isomers are part of structural isomers, 2 is not even an isomer its the same molecule

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