Nomenclature of organic compounds Questions in English

(B) The longest carbon chain contains $5$ carbon atoms,so the parent alkane is pentane.
Numbering the chain from either end gives substituents at positions $2, 3,$ and $4$.
The substituents are an ethyl group at $C-3$ and two methyl groups at $C-2$ and $C-4$.
According to alphabetical order,ethyl comes before methyl.
Therefore,the $IUPAC$ name is $3-$ethyl$-2,4-$dimethylpentane.

(B) The given structure is $CH_3-CH=CH-C\equiv CH$.
According to $IUPAC$ rules,the principal functional group is the one that gets the lowest possible locant.
Numbering from the right side gives the triple bond position $1$ and the double bond position $3$.
Numbering from the left side gives the double bond position $2$ and the triple bond position $4$.
Comparing the sets of locants $(1, 3)$ and $(2, 4)$,the set $(1, 3)$ is lower.
Therefore,the parent chain is $Pent$ and the name is $Pent-3-en-1-yne$.
Hence,the correct option is $B$.

(C) The $IUPAC$ name of the compound $CH_3-C(CH_3)=CH-COOH$ is determined by identifying the longest carbon chain containing the functional group and the double bond.
$1$. The principal functional group is the carboxylic acid $(-COOH)$,which is assigned $C1$.
$2$. The longest chain containing the double bond has $4$ carbon atoms,so the parent alkane is $butane$,and the acid is $butenoic \ acid$.
$3$. The double bond starts at $C2$,making it $but-2-enoic \ acid$.
$4$. There is a methyl group $(-CH_3)$ attached to $C3$.
$5$. Combining these,the name is $3$-methyl-$2$-butenoic acid.

(D) The structure is $CH_3-CH(C_2H_5)-C(CH_3)(C_4H_9)-CH_3$.
Expanding the alkyl groups: $CH_3-CH(CH_2CH_3)-C(CH_3)(CH_2CH_2CH_2CH_3)-CH_3$.
The longest carbon chain consists of $8$ carbon atoms (octane).
Numbering the chain to give the lowest locants for substituents: starting from the right end,the substituents are at positions $3, 4, 4$.
Thus,the $IUPAC$ name is $3,4,4-$trimethyloctane.

(A) $1$. Identify the principal functional group: The carboxylic acid group $(-COOH)$ has the highest priority,so the parent chain is named as an alkanoic acid.
$2$. Number the chain: Start numbering from the carbon of the $-COOH$ group as $C-1$. The chain is $C_1(OOH)-C_2H_2-C_3H=C_4(OH)-C_5H_3$.
$3$. Identify substituents and unsaturation: There is a hydroxyl group $(-OH)$ at $C-4$ and a double bond starting at $C-3$.
$4$. Combine the parts: The parent chain has $5$ carbons (pent),the double bond is at position $3$ (pent-$3$-ene),and the $-OH$ group is at position $4$. Combining these,we get $4-$hydroxypent-$3-$enoic acid.

(C) The given structure is $CH_3-C(C_2H_5)_2-CH_2Cl$.
Expanding the structure: $CH_3-C(CH_2CH_3)(CH_2CH_3)-CH_2Cl$.
The longest carbon chain containing the chlorine atom consists of $4$ carbon atoms (butane).
Numbering the chain starting from the carbon attached to the chlorine atom:
$C1: -CH_2Cl$
$C2: -C(CH_3)(CH_2CH_3)-$
$C3: -CH_2-$
$C4: -CH_3$
At $C2$,there are two substituents: an ethyl group $(-C_2H_5)$ and a methyl group $(-CH_3)$.
According to $IUPAC$ rules,substituents are listed alphabetically.
Therefore,the name is $1$-chloro-$2$-ethyl-$2$-methylbutane.

(A) The given compound is $CHO-(CH_2)_4-COOH$.
In $IUPAC$ nomenclature,the carboxylic acid group $(-COOH)$ is given priority over the aldehyde group $(-CHO)$.
The carbon of the carboxylic acid group is assigned position $1$.
Counting the carbon chain,we have $6$ carbons in total.
The aldehyde group at position $6$ is treated as a substituent and is named as '$oxo$' or '$formyl$'.
According to $IUPAC$ rules,when the carbon of the aldehyde group is not part of the principal chain,it is named as '$6$-oxohexanoic acid' or '$6$-formylhexanoic acid'. However,'$6$-oxohexanoic acid' is the standard $IUPAC$ name.

(A) The structure is $CH_3-CH=CH-COOH$.
Numbering starts from the carboxylic acid carbon as $C-1$.
The chain has $4$ carbon atoms,so the parent alkane is butane.
The double bond is at the $C-2$ position.
Therefore,the $IUPAC$ name is $but-2-enoic$ acid.

(A) The given structure is $(CH_3)_2CH-CHO$.
$1$. Identify the longest carbon chain containing the functional group (aldehyde).
$2$. The longest chain has $3$ carbon atoms,so the parent alkane is propane.
$3$. The aldehyde group $(-CHO)$ is assigned position $1$.
$4$. There is a methyl group $(-CH_3)$ attached to the $2^{nd}$ carbon atom.
$5$. Therefore,the $IUPAC$ name is $2-$methylpropanal.

(B) $1$. Identify the longest carbon chain containing the substituent groups. The longest chain has $5$ carbon atoms,which is a pentane chain.
$2$. Number the chain from the end that gives the substituents the lowest possible locants. Numbering from the right gives the methyl groups the position $2$.
$3$. The compound has two methyl groups at the $2^{nd}$ position. Thus,the name is $2, 2-$dimethylpentane.

(A) The given compound is $H_2C=CH-CH(CH_3)-CH_2-C \equiv CH$.
The parent chain contains $6$ carbon atoms,so the root word is $hex$.
The numbering starts from the end that gives the lowest locant to the multiple bonds. In this case,the double bond is at position $1$ and the triple bond is at position $5$.
According to $IUPAC$ rules,if both double and triple bonds are present,the double bond is given priority for numbering if they are at equivalent positions,but here the double bond at $C-1$ is preferred over the triple bond at $C-5$.
There is a methyl group at position $3$.
Therefore,the correct $IUPAC$ name is $3-$methyl$-1-$hexen$-5-$yne.

(D) $1$. Identify the longest carbon chain containing the double bond. The chain has $5$ carbon atoms,so the parent alkane is pentene.
$2$. Number the chain starting from the end closer to the double bond. The double bond starts at carbon $1$,so it is pent$-1-$ene.
$3$. Identify the substituents. There are two methyl groups at the $4$th position.
$4$. Combining these,the $IUPAC$ name is $4,4-$dimethylpent$-1-$ene.

(D) An isopropyl group is represented by the structure $(CH_3)_2CH-$.
$1.$ $2, 2, 3, 3-$tetramethylpentane: All methyl groups are attached to quaternary carbons,so no isopropyl group is present.
$2.$ $2, 2-$dimethylpentane: The structure is $CH_3-CH_2-CH_2-C(CH_3)_2-CH_3$. It contains a tert-butyl group,not an isopropyl group.
$3.$ $2, 2, 3-$trimethylpentane: The structure is $CH_3-C(CH_3)_2-CH(CH_3)-CH_2-CH_3$. It contains a tert-butyl group and a sec-butyl group,but no isopropyl group.
$4.$ $2-$methylpentane: The structure is $(CH_3)_2CH-CH_2-CH_2-CH_3$. This compound contains one isopropyl group at the $2-$position.

(A) $1$. Identify the longest carbon chain containing the principal functional group $(-OH)$. The chain has $7$ carbons,so the parent alkane is heptane.
$2$. Number the chain from the end that gives the lowest locant to the principal functional group $(-OH)$. Numbering from left to right gives the $-OH$ group at position $2$.
$3$. Identify substituents: There are two bromine atoms at position $6$. Thus,the prefix is $6, 6-$dibromo.
$4$. Combine the parts: The $IUPAC$ name is $6, 6-$dibromoheptan$-2-$ol.

(C) The longest carbon chain containing the functional groups has $5$ carbon atoms,making it a pentane derivative.
Numbering the chain from the right side gives the hydroxyl groups positions $2$ and $4$,and the methyl group position $2$.
This provides the lowest possible locants for the substituents and functional groups.
Therefore,the $IUPAC$ name is $2-$methyl$-2, 4-$pentanediol.

(A) $1$. In cyclic alkenes,the double bond is assigned the position $1$ and $2$.
$2$. The numbering should be done in such a way that the substituent gets the lowest possible locant.
$3$. Starting from the double bond,if we number the carbon atoms of the double bond as $1$ and $2$,the methyl group attached to the next carbon will be at position $3$.
$4$. Therefore,the correct $IUPAC$ name is $3-$methylcyclohexene.

(C) The structure is $CH_3-C(CH_3)=CH-CH_2OH$.
According to $IUPAC$ rules,the principal functional group $(-OH)$ gets the lowest possible locant.
Numbering starts from the carbon attached to the $-OH$ group: $C_1$ is $CH_2$,$C_2$ is $CH$,$C_3$ is $C(CH_3)$,and $C_4$ is $CH_3$.
The double bond is at position $2$,and there is a methyl group at position $3$.
Thus,the name is $3-$methylbut-$2-$en-$1-$ol.

(A) The given structure is $CH_3-C \equiv C-CH(CH_3)_2$.
To determine the $IUPAC$ name,we first identify the longest carbon chain containing the triple bond.
The longest chain has $5$ carbon atoms,so the parent alkane is pentane,and with the triple bond,it becomes pentyne.
Numbering the chain from the left gives the triple bond the lowest possible locant,which is $2$.
There is a methyl group attached to the $4^{th}$ carbon.
Thus,the correct $IUPAC$ name is $4-$methylpent$-2-$yne.
Therefore,the correct option is $(A)$.

(D) Let us analyze each option:
$A$: $CH_3-CH_2-CH_2-COOCH_2CH_3$ is an ester. The alkyl group attached to oxygen is ethyl,and the acid part is butanoate. The name is correct.
$B$: $CH_3-CH(CH_3)-CH_2-CHO$. The longest chain has $4$ carbons. The methyl group is at position $3$. The name $3$-methylbutanal is correct.
$C$: $CH_3-CH(OH)-CH(CH_3)-CH_3$. The longest chain has $4$ carbons. The hydroxyl group is at position $2$ and the methyl group is at position $3$. The name $3$-methylbutan-$2$-ol is correct.
$D$: $CH_3-CH(CH_3)-CO-CH_2-CH_3$. The longest chain has $5$ carbons. The ketone group is at position $3$. The methyl group is at position $2$. The correct name is $2$-methylpentan-$3$-one. Wait,let us re-check the numbering. Numbering from the left gives the ketone at $3$ and methyl at $2$. Numbering from the right gives the ketone at $3$ and methyl at $4$. Thus,$2$-methylpentan-$3$-one is correct.
Actually,looking at the structure in option $D$,the formula provided is $CH_3-CH(CH_3)-CO-CH_2-CH_3$. This is $2$-methylpentan-$3$-one. All names provided are correct. However,if we assume a typo in the question's intent,usually one of these is designed to be wrong. Given the options,all are technically correct $IUPAC$ names.

(A) The chemical structure of $n-$butyl chloride is $CH_3-CH_2-CH_2-CH_2-Cl$.
In the $IUPAC$ nomenclature system,the longest carbon chain containing the functional group (chlorine) is selected.
Here,the chain has $4$ carbon atoms,so the parent alkane is butane.
The chlorine atom is attached to the first carbon atom.
Therefore,the $IUPAC$ name is $1-$chlorobutane.

(A) $1$. Identify the principal functional group: The compound contains an acyl chloride group $(-COCl)$,which is the principal functional group. The carbon atom of the $-COCl$ group is assigned position $1$.
$2$. Select the longest carbon chain containing the principal functional group: The longest chain containing the $-COCl$ group has $5$ carbon atoms. Thus,the parent alkane is pentane,and the suffix is 'oyl chloride'.
$3$. Number the chain: Starting from the $-COCl$ carbon as $1$,the methyl group $(-CH_3)$ is at position $3$.
$4$. Combine the parts: The name is $3-$methylpentanoyl chloride.

(C) The given structure is $CH_3-CH(CH_3)-CH(OH)-CH_3$.
$1$. Identify the longest carbon chain containing the functional group $(-OH)$. The longest chain has $4$ carbon atoms,so the parent alkane is butane.
$2$. Number the chain from the end that gives the lowest locant to the functional group $(-OH)$. Numbering from right to left gives the $-OH$ group at position $2$.
$3$. Identify the substituent: there is a methyl group $(-CH_3)$ at position $3$.
$4$. Combining these,the name is $3-$methylbutan$-2-$ol or $3-$methyl butanol$-2$.

(A) To name the compound $ClH_2C-C(Br)=C(Br)-CH_2Cl$ according to $IUPAC$ rules:
$1$. Identify the longest carbon chain containing the double bond,which is a $4$-carbon chain (but$-2-$ene).
$2$. Number the chain from either end to give the lowest locants to the substituents. Numbering from either side gives $1,4$-dichloro-$2,3$-dibromo.
$3$. Alphabetize the substituents: 'bromo' comes before 'chloro'.
$4$. Combining these,the name is $2,3$-dibromo-$1,4$-dichlorobut-$2$-ene.

(A) The structure of acraldehyde is $CH_2=CH-CHO$.
The parent carbon chain consists of three carbon atoms,so the word root is $prop$.
The double bond is present at the second carbon,and the functional group is an aldehyde,which uses the suffix $-al$.
Therefore,the $IUPAC$ name is $Prop-2-en-1-al$.

(A) $1$. Identify the longest carbon chain containing the principal functional group $(-OH)$. The longest chain has $5$ carbon atoms,so the parent alkane is pentane.
$2$. Number the chain from the end that gives the lowest locant to the functional group. Numbering from left to right gives the $-OH$ group at position $2$.
$3$. Identify the substituents: there is a methyl group $(-CH_3)$ at position $4$.
$4$. Combining these,the name is $4-$methylpentan$-2-$ol.

(D) The double bond is given priority over the triple bond when numbering the carbon chain.
Numbering starts from the end that gives the double bond the lowest possible locant.
Thus,the chain is numbered from left to right: $\stackrel{1}{CH_2}=\stackrel{2}{CH}-\stackrel{3}{CH_2}-\stackrel{4}{CH_2}-\stackrel{5}{C}\equiv\stackrel{6}{CH}$.
The parent chain has $6$ carbons,so the root is 'hex'.
The double bond is at position $1$ and the triple bond is at position $5$.
Therefore,the $IUPAC$ name is $1-$hexene$-5-$yne.

(B) The principal functional group is the aldehyde $(-CHO)$,which is assigned the lowest locant $(1)$.
The longest carbon chain containing the aldehyde group has $5$ carbon atoms,so the parent alkane is pentane.
Numbering starts from the aldehyde carbon as $C-1$.
The methyl group $(-CH_3)$ is at position $C-4$ and the hydroxyl group $(-OH)$ is at position $C-2$.
Alphabetically,'hydroxy' precedes 'methyl'.
Therefore,the correct $IUPAC$ name is $2-$hydroxy$-4-$methylpentanal.

(B) $1$. Identify the longest carbon chain containing the double bond. The chain has $6$ carbon atoms,so the parent alkane is hexane.
$2$. Number the chain from the end that gives the double bond the lowest possible locant. Numbering from the right gives the double bond position at $2$.
$3$. The substituent is a methyl group at position $4$.
$4$. Combining these,the name is $4-$methyl$-2-$hexene.

(B) $1$. Identify the longest carbon chain containing the functional group (nitrile group). The chain has $6$ carbons,so the parent alkane is hexane.
$2$. Number the chain starting from the nitrile carbon as $C-1$.
$3$. The nitrile group is at $C-1$,so the suffix is $nitrile$.
$4$. There is a methyl group at the $4^{th}$ carbon.
$5$. The correct $IUPAC$ name is $4-$methylhexanenitrile.

(D) The structure is $CH_3-CH=CH-CH=CH-CH_3$.
There are two double bonds at positions $2$ and $4$.
For the double bond at $C2$,the higher priority groups ($-CH_3$ and the rest of the chain) are on opposite sides,indicating an $E$ configuration.
For the double bond at $C4$,the higher priority groups are also on opposite sides,indicating an $E$ configuration.
Therefore,the correct name is $(2E, 4E)-2, 4-\text{hexadiene}$.

(C) The given compound is $HOOC-CH_2-CH(COOH)-CH_2-CH_2-COOH$.
According to the $IUPAC$ rules,when more than two carboxylic acid groups are present on an unbranched alkane chain,the carbon atoms of the $-COOH$ groups are not included in the parent chain.
The parent chain is the longest carbon chain containing all the carbons to which the $-COOH$ groups are attached.
Here,the parent chain is butane ($4$ carbons),and the $-COOH$ groups are at positions $1, 2,$ and $4$.
Therefore,the name is Butane$-1, 2, 4-$tricarboxylic acid.

(D) In $IUPAC$ nomenclature,substituents are listed in alphabetical order.
For the compound $CH_3-CH_2-CH_2-CH(C_2H_5)-CH(CH_3)-CH_2-CH_3$,the parent chain is heptane.
The substituents are ethyl at position $4$ and methyl at position $3$.
Alphabetically,'ethyl' comes before 'methyl'.
Therefore,the correct name should be $4-\text{Ethyl-}3-\text{methylheptane}$.
Thus,the name $3-\text{Methyl-}4-\text{ethylheptane}$ is incorrect.

(A) The principal functional group is $-OH$,so the parent chain is numbered to give the $-OH$ group the lowest possible number.
$\overset{4}{C}H_3-\overset{3}{C}H_2-\overset{2}{C}H(OCH_3)-\overset{1}{C}H_2-OH$
The longest chain has $4$ carbon atoms (butane).
There is a methoxy $(-OCH_3)$ group at the $2$nd carbon.
Therefore,the $IUPAC$ name is $2$-methoxy-$1$-butanol.

(D) The given structure is $CH_3-CH(NH_2)-CH_3$.
The longest carbon chain contains $3$ carbon atoms,so the parent alkane is propane.
The amino group $(-NH_2)$ is attached to the second carbon atom.
Therefore,the $IUPAC$ name is $2$-propanamine.

(A) The given structure is $CH_3-CH(Cl)-CH_3$.
The longest carbon chain contains $3$ carbon atoms,so the parent alkane is propane.
The chlorine atom is attached to the second carbon atom.
Therefore,the $IUPAC$ name is $2-$chloropropane.

(B) The correct option is $B$.
For the first structure $CH_3-CH(OH)-CH_2-C(CH_3)(OH)-CH_3$:
The longest carbon chain containing the principal functional groups $(-OH)$ has $5$ carbons.
Numbering is done to give the lowest locants to the $-OH$ groups,which are at positions $2$ and $4$ from either side.
Next,we apply the lowest locant rule for the substituent (methyl group). Numbering from right to left gives the methyl group position $2$,while left to right gives position $4$.
Thus,the correct $IUPAC$ name is $2$-methyl-$2,4$-pentanediol.
For the second structure $CH_2(CN)-CH(CN)-CH_2(CN)$:
According to $IUPAC$ rules,the longest carbon chain containing the principal functional groups $(-CN)$ is selected.
Here,the chain is $5$ carbons long (pentane),with nitrile groups at positions $1$ and $5$.
The third $-CN$ group is treated as a substituent at position $3$,named as a cyano group.
Thus,the $IUPAC$ name is $3$-cyano-$1,5$-pentanedinitrile.

(A) The structure is $CH_3-CH_2-C(Br)=CHCl$.
According to $IUPAC$ nomenclature rules,we number the chain starting from the end that gives the double bond the lowest possible locant.
Here,the double bond is between $C_1$ and $C_2$.
Numbering from the right,$C_1$ has the $Cl$ atom,$C_2$ has the $Br$ atom,and the chain is a $but-1-ene$ derivative.
Thus,the correct name is $2-$bromo$-1-$chlorobut$-1-$ene.

(B) The given compound is a six-membered cyclic ketone with a methyl group attached to the carbon adjacent to the carbonyl group.
According to $IUPAC$ nomenclature rules for cyclic ketones,the carbonyl carbon is assigned position $1$.
Numbering the ring to give the substituent the lowest possible locant,the methyl group is at position $2$.
Therefore,the $IUPAC$ name is $2$-methylcyclohexanone.

(B) $1$. Identify the longest carbon chain containing the maximum number of double bonds. The chain has $5$ carbons,so it is a pentadiene derivative.
$2$. Number the chain from the end that gives the lowest locants to the substituents and double bonds. Numbering from right to left gives the double bonds at positions $1$ and $4$,and substituents at $2$ $(Br)$ and $3$ $(ethyl)$.
$3$. The name is $2-$bromo$-3-$ethyl$-1, 4-$pentadiene.

(D) The given compound is $CH_3CH_2COOH$.
$1$. Identify the longest carbon chain containing the functional group $(-COOH)$. The chain has $3$ carbon atoms.
$2$. For a $3$-carbon chain,the parent alkane is propane.
$3$. The suffix for carboxylic acid is $-oic \ acid$.
$4$. Combining these,the $IUPAC$ name is $Propanoic \ acid$.

(C) $1$. Identify the longest carbon chain containing the principal functional group $(-OH)$. The chain has $6$ carbons,so the parent alkane is hexane.
$2$. Number the chain from the end closer to the $-OH$ group: $C_1$ is $CH_2Cl$,$C_2$ is $CH(OH)$,$C_3$ is $CH_2$,$C_4$ is $CH(CH_2CH_3)$,$C_5$ is $CH_2$,and $C_6$ is $CH_3$.
$3$. Substituents are: $1-chloro$ and $4-methyl$ (since the ethyl group at $C_4$ is part of the main chain,the remaining $CH_3$ is the substituent).
$4$. Combining these,the name is $1-chloro-4-methylhexan-2-ol$ or $1-chloro-4-methyl-2-hexanol$.

(C) The structure is $(CH_3)_3C-CH=CH_2$.
$1$. Identify the longest carbon chain containing the double bond: The longest chain has $4$ carbon atoms,so the parent alkane is butane,and with the double bond,it is but$-1-$ene.
$2$. Number the chain starting from the end closer to the double bond: $C_1=CH_2$,$C_2=CH$,$C_3=C(CH_3)_2$,$C_4=CH_3$.
$3$. Identify substituents: There are two methyl groups at the $C_3$ position.
$4$. Combine the parts: $3,3-$dimethylbut$-1-$ene.

(D) The structure is $CH_3-CO-CH(CH_3)_2$.
The longest carbon chain containing the ketone functional group consists of $4$ carbon atoms.
Numbering the chain from the end that gives the ketone group the lowest possible locant,we start from the left: $C_1$ is $CH_3$,$C_2$ is $CO$,$C_3$ is $CH(CH_3)$,and $C_4$ is $CH_3$.
There is a methyl substituent at the $C_3$ position.
Therefore,the $IUPAC$ name is $3-$methylbutan$-2-$one or $3-$methyl$-2-$butanone.

(B) The given structure is $CH_3-CH(C_2H_5)-CH(CH_3)-CH_2-CH(C_2H_5)-CH_3$.
Expanding the structure: $CH_3-CH_2-CH(CH_3)-CH(CH_3)-CH_2-CH(CH_3)-CH_2-CH_3$.
The longest carbon chain contains $8$ carbon atoms,so the parent alkane is octane.
Numbering from the left gives substituents at positions $3, 4, 6$.
Numbering from the right gives substituents at positions $3, 5, 6$.
Comparing the locant sets $(3, 4, 6)$ and $(3, 5, 6)$,the set $(3, 4, 6)$ is lower.
Therefore,the correct $IUPAC$ name is $3,4,6-trimethyloctane$.

(A) $1$. Identify the longest carbon chain containing the double bond: The chain has $5$ carbons,so the parent alkane is pentene.
$2$. Number the chain starting from the end that gives the double bond the lowest locant: Numbering from left to right,the double bond starts at $C-2$.
$3$. Identify substituents: There is a chloro group at $C-2$ and a methyl group at $C-4$.
$4$. Combine the parts alphabetically: $2-$chloro$-4-$methylpent$-2-$ene.

(D) The structure is $\mathop{CH_3}\limits^{1} - \mathop{CO}\limits^{2} - \mathop{CH_3}\limits^{3}$.
Ketones are named by replacing the suffix '$-e$' of the corresponding alkane with '$-one$'.
Since the parent chain has $3$ carbon atoms,the alkane is propane.
Replacing '$-e$' with '$-one$' gives propanone.

(B) $1$. Identify the longest carbon chain. The longest chain contains $8$ carbon atoms,so the parent alkane is octane.
$2$. Number the chain from the end that gives the substituents the lowest possible locants. Numbering from left to right gives substituents at positions $3$ and $5$.
$3$. The substituent at position $3$ is a methyl group $(-CH_3)$.
$4$. The substituent at position $5$ is a $1-$methylethyl group (also known as an isopropyl group).
$5$. According to $IUPAC$ nomenclature rules,complex substituents are named in parentheses. Thus,the name is $3-$methyl$-5-(1'-$methylethyl$)$ octane.

(A) The parent functional group is the aldehyde $(-CHO)$,so the benzene ring with the aldehyde group is named as benzaldehyde.
Numbering starts from the carbon attached to the $-CHO$ group as $1$.
The $-NO_2$ group is at position $2$ and the $-OCH_3$ (methoxy) group is at position $4$.
Therefore,the correct $IUPAC$ name is $4-$methoxy$-2-$nitrobenzaldehyde.