How are the following pairs related?

(i) 2, 2-dimethylpropane and 2-methylbutane


(ii) Ethane and propane


(iii) C2H5C1 and C3H7Cl


(iv) C3H4 and C2H4

(i) The structural formula of the two compounds are shown below.



2,2-dimethylpropane



2-methylbutane


Note that both compounds have the same molecular formula C5H12. Since they have same molecular formula but different structural formula, they are isomers.


(ii) Ethane (C2H6) and propane (C3H8) can be represented by the general formula CnH2n+2 where ‘n’ is the number of carbon atoms. Also they differ by a –CH2 unit. Hence they are homologues.


(iii) C2H5Cl and C3H7Cl differ by a –CH2 unit. Also these 2 can be represented by the formula CnH2n+1Cl. Therefore they are homologues.


(iv) C3H4 is an alkyne and C2H4 is an alkene. Both the compounds contain double or triple bonds. Therefore, they belong to the family of unsaturated compounds.


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