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Question
Write the molecular formula of the 2nd and 3rd member of the homologous series where the first member is ethyne.
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Solution
The general formula for the homologous series whose first member is ethyne is CnH2n - 2.
The two consecutive members (2nd and 3rd) of this series are:
a. CH3C≡CH (Propyne); where n is 3
b. CH3CH2C≡CH(1-Butyne) or CH3C≡CCH3 (2-Butyne); where n is 4
The molecular formulae are C3H4 and C4H6, respectively.
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