M/J 2019/P11/Q33
Compound Q is a hydrocarbon that has no isomers. Compound Q does not decolourise bromine in the dark.
Which compound could be Q?
A C3H6 B C3H8 C C4H8 D C4H10
Answer: B
Explaination
Option A and C are alkenes
Option B and D are alkenes
Alkenes addition reaction is bromination in which bromine add across the double bond of alkene. This reaction serves as a chemical test for the presence of unsaturated HC. It is used to distinguish between an alkane and an alkene. Alkanes do not decolourise bromine solution because of the single bond but alkenes decolourise bromine solution rapidly.
Option B is propane C3H8
Option D is butane C4H10
So, compound Q is option B “propane” as it has no isomers because isomerism starts from butane in alkane series.
