Q20 of 23 Page 4

Why are certain compounds called hydrocarbons? Write the general formula for homologous series of alkanes, alkenes, and alkynes and also draw the structure of the first member of each series. Write the name of the reaction that converts alkenes into alkanes and also writes a chemical equation to show the necessary conditions for the reaction to occur.(CBSE 2017)

Certain compounds are called hydrocarbons as they are made up of carbon and hydrogen only.

Alkanes general formula is CnH2n+2



methane


Alkenes general formula is CnH2n



Alkyne is CnH2n-2



Hydrogenation reaction converts alkenes into alkanes in presence of catalyst nickel.


CH2=CH2 + H2 → CH3-CH3

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