Question

The decreasing order of acidic character among ethane (I), ethene (II),ethyne (III) and propyne (IV) is
A. (I) gt (II) gt (III) gt (IV)
B. (II) gt (III) gt (I) gt (IV)
C. (III) gt (IV) gt (II) gt (I)
D. (IV) gt (III) gt (II) gt (I)

Answer 1

Correct Answer - C
The correct order of decreasing acidity is `underset"(III)"(CH-=CH)gt underset"(IV)"(CH-=C-CH_3)gt underset"(II)"(CH_3=CH_2)gt underset"(I)"(CH_3-CH_3)`
Hydrocarbon atoms attached to sp-hybridised carbon atom are most acidic , followed by those attached to `sp^2`-hybridised carbon -atom, and those attached to `sp^3`-hybridised carbon are least acidic.