Counting structural isomers

55 questions on Counting structural isomers from the IUPAC Nomenclature and Structural Isomerism chapter: 11 NEET level, 22 JEE Main, 22 JEE Advanced. Each one opens with its answer and solution.

• How many structural isomers does the alkane C6H14 have? Count structural isomers only (no stereoisomers). NEET level
• The number of different alkyl groups (structural, no stereoisomers) of formula C4H9 is NEET level
• Pentane, CH3CH2CH2CH2CH3, is monochlorinated under free-radical conditions. How many different monochloro structural isomers are possible? NEET level
• Open-chain ethers of molecular formula C4H10O number (structural isomers only) NEET level
• The number of aromatic (benzene ring containing) structural isomers of C8H10 is NEET level
• How many structural isomers are possible for dichlorobenzene, C6H4Cl2? NEET level
• The number of saturated acyclic carbonyl compounds (aldehydes and ketones, no other functional group) of formula C4H8O is NEET level
• How many carboxylic acids (structural isomers) have the molecular formula C5H10O2? NEET level
• The number of primary amines (structural isomers) of formula C3H9N is NEET level
• The number of esters (structural isomers) with formula C4H8O2 is NEET level
• How many monochloro derivatives (structural isomers) can be obtained from 2,2-dimethylpropane by substitution of one hydrogen? NEET level
• Free-radical monochlorination of 2-methylbutane gives how many different structural isomers of C5H11Cl (stereoisomers not counted)? JEE Main level
• 2,2,4-Trimethylpentane (isooctane), (CH3)3C-CH2-CH(CH3)2, is monochlorinated. The number of structural isomers of the product C8H17Cl is JEE Main level
• Propane is dichlorinated. How many structural isomers of C3H6Cl2 can form (stereoisomers not counted)? JEE Main level
• The number of dichloro derivatives (structural isomers) of neopentane, 2,2-dimethylpropane, is JEE Main level
• Trichlorobenzene, C6H3Cl3, exists as how many structural isomers? JEE Main level
• The number of aromatic (benzene ring containing) structural isomers of C7H8O is JEE Main level
• Ethers of formula C5H12O (open-chain, structural isomers) number JEE Main level
• How many secondary alcohols are there among the open-chain saturated alcohols of molecular formula C5H12O? JEE Main level
• Tertiary alcohols of formula C6H14O (structural isomers, open chain) number JEE Main level
• How many open-chain alkenes (structural isomers only) are there with the formula C5H10? JEE Main level
• The number of alkyne isomers (open-chain, structural) of C5H8 is JEE Main level
• Counting every ring system that contains only carbon atoms, ring-substituted or not, the number of cycloalkane structural isomers of C5H10 (stereoisomers not co... JEE Main level
• The number of primary amines (structural isomers) of formula C4H11N is JEE Main level
• The number of secondary amines (structural isomers) of formula C4H11N is JEE Main level
• Considering nitroalkanes R-NO2 and alkyl nitrites R-O-N=O together, the number of structural isomers of formula C3H7NO2 is JEE Main level
• Among the open-chain ethers of formula C5H12O, how many contain at least one branched alkyl group (isopropyl, sec-butyl, isobutyl or tert-butyl; structural isom... JEE Main level
• The number of open-chain amides (including N-substituted amides and formamides; the -CO-N unit must be present) of formula C3H7NO is JEE Main level
• Which of the following statements about numbers of structural isomers (stereoisomers not counted) is/are correct? JEE Main level
• Which of the following pairs are structural isomers of each other? JEE Main level
• Which of the following alkanes give exactly three different monochloro derivatives (structural isomers) on free-radical chlorination? JEE Main level
• Which of the following statements about halogen-substituted benzene rings (structural isomers) is/are correct? JEE Main level
• n-Butane is dichlorinated by free-radical substitution. How many structural isomers of C4H8Cl2 can be formed in total (stereoisomers not counted)? Give an integ... JEE Main level
• All possible dichloro substitution products C5H10Cl2 of 2-methylbutane are considered. How many structural isomers (no stereoisomers counted) are possible? JEE Advanced level
• The number of dichloro derivatives (structural isomers, stereoisomers not counted) of 2-methylpropane is JEE Advanced level
• Methylcyclopropane is dichlorinated on the ring or the side chain. How many dichloro structural isomers of C4H6Cl2 are possible (stereoisomers not counted)? JEE Advanced level
• If each of the five isomeric hexanes is monochlorinated and all possible structural isomers of C6H13Cl are collected, what is the total number of distinct monoc... JEE Advanced level
• Open-chain saturated alcohols of formula C5H12O that give a positive iodoform test (the unit CH3-CH(OH)- must be present) number JEE Advanced level
• Saturated open-chain carbonyl compounds (aldehydes and ketones) of formula C5H10O are considered. How many of them give a positive Tollens' test or a positive i... JEE Advanced level
• The number of open-chain amides (primary, secondary and tertiary, formamides included) of formula C4H9NO, structural isomers only, is JEE Advanced level
• Aromatic hydrocarbons (containing one benzene ring) of formula C9H12 exist as how many structural isomers? JEE Advanced level
• Chlorine replaces two hydrogen atoms of toluene (on the ring and/or on the methyl group), giving C7H6Cl2 with the benzene ring retained. How many structural iso... JEE Advanced level
• Chlorine, bromine and a hydroxyl group are attached to three different carbons of a benzene ring (compounds C6H3Br(Cl)OH). The number of structural isomers is JEE Advanced level
• Open-chain alcohols of formula C5H12O are treated with acidified potassium dichromate. How many of the isomers can be oxidised (to an aldehyde/acid or ketone) w... JEE Advanced level
• Esters of formula C5H10O2 (structural isomers) are hydrolysed. How many of them give a secondary or a tertiary alcohol (as the alcohol component)? JEE Advanced level
• The total number of amines (primary + secondary + tertiary, open-chain, structural isomers) of formula C5H13N is JEE Advanced level
• Of the nine structural isomers of heptane, C7H16, how many contain a quaternary carbon (a carbon bonded to four other carbon atoms)? JEE Advanced level
• Which of the following statements about open-chain isomers of C5H12O (alcohols and ethers, structural isomers only) is/are correct? JEE Advanced level
• Which of the following classes contain exactly 4 structural isomers? JEE Advanced level
• Which of the following alkanes give exactly one monochloro derivative on free-radical chlorination? JEE Advanced level
• Which of the following statements about dichloro derivatives (structural isomers, no stereoisomers) is/are correct? JEE Advanced level
• Which of the following statements about aromatic (benzene ring containing) structural isomers is/are correct? JEE Advanced level
• Which of the following sets contain only compounds that are structural isomers of one another? JEE Advanced level
• Which of the following statements about saturated open-chain aldehydes and ketones of formula C5H10O (structural isomers only) is/are correct? JEE Advanced level
• How many open-chain alkenes (one C=C, no rings) of molecular formula C6H12 exist if only structural isomers are counted (cis/trans isomers are not counted separ... JEE Advanced level