Explanation:
1. count the no. of carbon in longest chain or back bone of Carbone
2. if any substituent is present, give a smallest position
3.in the case of functional group you need to identify what is main functional group and substituent
eg. CH3-CH2-CH(Cl)-CH-(C2H5)
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CHO
Here aldehyde (-CHO) is main functional group so the counting starts from aldehyde and chlorine (-Cl) is substituent and ethyl is another substituent get 3,2 position and 5 carbon present in carbon chain
IUPAC name of given compound = 2-(ethyl)-3-(chloro)-pentanal
