The decreasing order of acidic character among ethane (I), ethene (II), ethyne (III) and propyne (IV) is

Options

A. `(I) gt (II) gt (II) 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

C

Explanation

The correct order of decreasing acidity is
`underset((III))(CH-=CH) gt underset((IV))(CH-=C-CH_(3))gt underset((II))(CH_(2)=CH_(2)) gt underset((I))(CH_(3)-CH_(3))`
Hydrogen 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.