Question

The CORRECT increasing order of acidity of the following hydrocarbons is: 

Propyne	Propane	Ethene	Ethyne
(I)	(II)	(III)	(IV)

Options

• III < I <II < IV

• II< I< IV< III

• II < III < I < IV

• II< IV< I< III

Answer 1

II < III < I < IV

Explanation:

Ethyne is more acidic than other substances because it has two terminal hydrogen atoms bound to sp-hybridized carbon, which is extremely electronegative: Due to the +I effect, acidity reduces as the number of alkyl groups on sp-hybridized carbon increases. Consequently, the given compounds' true ascending order of acidity is,

Propane < Ethene < Propyne < Ethyne

    (II)            (III)            (I)            (IV)