Which formula can represent an alkyne?

June 2018 NY Regents Chemistry Exam

21 Which formula can represent an alkyne?
(1) C2H4

(2) C2H6

(3) C3H4

(4) C3H6

Solution: Table Q on the Reference Table shows Homologous Series of Hydrocarbons. It shows names and general formula. The formula for an alkyne is CnH2n – 2. If we take a look at C3H1, n=3. 3*2-2 = 6-2=4. It is an alkyne

Answer: 3

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