M/J 2017/P11/Q36
Molecules 1–4 are unbranched hydrocarbons.
Which row correctly identifies these hydrocarbons as alkanes or alkenes?
Answer: A
Explaination:
Alkane doesn’t undergo addition reaction with bromine instead alkane undergoes substitution reaction with bromine/chlorine. However, Alkene undergoes addition reaction with bromine so by putting the values of “n” from molecular formula into general formula we can get the correct answer.
(Alkene: CnH2n, Alkane: CnH2n+2)
Option W: C9H18
C9H2 (9) = C9H18
Option X: C9H20
C9H2 (9) +2 = C9H20
Option Y: C10H20
C10H2 (10) = C10H20
Option Z: C10H22
C10H2 (10)+2 = C10H22
Hence options W & Y are alkenes as they put correctly in general formula of alkene so they undergo addition reaction whereas, options X & Z are alkanes.
