Which is incorrect numbering in the following | vedclass

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(D) According to $IUPAC$ nomenclature rules for unsaturated hydrocarbons containing both double and triple bonds:$1$. The principal chain is selected

Vedclass · Accepted Answer

Hepta$-1,4-$dien$-6-$yne

Vedclass · Answer

(D) According to $IUPAC$ nomenclature rules for unsaturated hydrocarbons containing both double and triple bonds:$1$. The principal chain is selected such that it contains both the double and triple bonds,if possible.$2$. Numbering is done such that the set of locants for the multiple bonds is as low as possible.$3$. If there is a tie in the locant set (e.g.,$1, 5$ vs $1, 5$),the double bond is given preference over the triple bond for the lower number.Analyzing the options:- Option $A$: $CH_2=CH-CH_2-CH_2-C\equiv CH$. Numbering from left gives locants $1$ (ene) and $5$ (yne). This is correct.- Option $B$: $CH\equiv C-CH_2-CH=CH-CH_3$. Numbering from right gives locants $1$ (yne) and $5$ (ene). This is correct.- Option $C$: $CH_2=CH-CH_2-CH=CH-C\equiv CH$. Numbering from left gives locants $1, 4$ (enes) and $6$ (yne). This is correct.- Option $D$: $CH_2=CH-CH_2-CH=CH-C\equiv CH$. The numbering shown in the image is $1, 2, 3, 4, 5, 6, 7$. The double bonds are at $1$ and $4$,and the triple bond is at $6$. However,the structure shown in the image for $D$ labels the triple bond at $6$ but the numbering sequence is inconsistent with the chain length or connectivity compared to standard $IUPAC$ rules for this specific structure. Specifically,the numbering in $D$ is $1, 2, 3, 4, 5, 6, 7$ where the double bond is at $4$ and $5$ in the image,which is incorrect as the double bond should be at $4$ and $5$ but the numbering $4-5$ is written as $4$ and $5$ on the same bond,which is invalid.

Which is incorrect numbering in the following compounds as per $IUPAC$ rules?

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