Question

Give the general formula of 'alkynes'. Identify the alkynes from the following:
`CH_(4),C_(2)H_(6),C_(2)H_(2),C_(3)H_(4),C_(2)H_(4)`

Answer 1

The general formula of alkynes is `CnH_(2n-2)` whsere n is the number of carbon atoms in one molecule of the alkyne . Out of the above given hydrocarbons `C_(2)H_(2) and C_(3)H_(4)` are alkynes (because they correspond to the general formula `C_(n)H_(2n-2)` with n=2 and n=3, respectively) (please note that in an alkyne molecule, ' the number of hydrogen atoms' is ' 2 less than double the number of carbon atoms')