IMAT 2013 Q47 [Organic Isomers]

Which of the following must be correct about organic isomers?

  1. They have the same molecular formulae.
  2. Their physical properties are very similar.
  3. They have different structural formulae.

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

Isomers are compounds that have the same empirical and molecular formula, but different structural or spatial arrangements of the atoms within the molecule. Since they may have different functional groups, we cannot assume their properties should stay the same.

From what we have just stated and must know, we can safely say 1 and 3 are correct.

2 is incorrect since we know their properties can be different based on their functional groups.

Therefore E is our answer.