CBSE Class 10 Answered

       Alkanes:  A common "ane" suffix identifies these compounds as alkanes.

            IUPAC Rules for Alkane Nomenclature

     1. Find and name the longest continuous carbon chain.
     2. Identify and name groups attached to this chain.
     3. Number the chain consecutively, starting at the end nearest a substituent group.
     4. Designate the location of each substituent group by an appropriate number and name.
     5. Assemble the name, listing groups in alphabetical order using the full name (e.g. cyclopropyl before isobutyl).
          The prefixes di, tri, tetra etc., used to designate several groups of the same kind, are not considered when alphabetizing.

Alkenes :

IUPAC Rules for Alkene and Cycloalkene Nomenclature

1. The ene suffix (ending) indicates an alkene or cycloalkene.
2. The longest chain chosen for the root name must include both carbon atoms of the double bond.
3. The root chain must be numbered from the end nearest a double bond carbon atom. If the double bond is in the center of the chain, the nearest substituent rule is used to determine the end where numbering starts.
4. The smaller of the two numbers designating the carbon atoms of the double bond is used as the double bond locator. If more than one double bond is present the compound is named as a diene, triene or equivalent prefix indicating the number of double bonds, and each double bond is assigned a locator number.
5. In cycloalkenes the double bond carbons are assigned ring locations #1 and #2. Which of the two is #1 may be determined by the nearest substituent rule.
6. Substituent groups containing double bonds are:
H₂C=CH– Vinyl group
H₂C=CH–CH₂– Allyl group

Alkynes