MCQ on Isomerism Pdf for NEET
Practicing these MCQ on Isomerism for class 11 will help you to answer every question that is being asked in the board exams as well as in NEET Exam also. Students can solve these Isomerism MCQ for NEET Pdf Download to know their preparation level. Isomerism Objective type Questions help the students to understand the concepts thoroughly and to score good marks in NEET. The below Multiple Choice Questions on Isomerism with answers Pdf have been prepared as per the latest syllabus. Practice it now and score high in NEET exam.
Two or more than two compounds having the same molecular formula but different physical/chemical or both properties are called isomers and the phenomenon is called isomerism. Chain Isomerism (C.I.) : The compounds which have same molecular formula, same functional group but different arrangement of carbon chain (Parental or side chain) show chain isomerism. Position Isomerism (P.I.) : The compounds which have same molecular formula, same functional group, same parent carbon chain but different position of functional group or multiple bond or substituents, show position isomerism.
Functional Isomerism : Same molecular formula but different functional groups. Metamerism : Same molecular formula, same polyvalent Functional group but different alkyl groups attached to polyvalent Functional group. Stereo Isomerism : Two or more than two compounds having same molecular formula, same structural formula but different arrangements of atoms or groups in space.
Optical isomers : Two or more than two compound have same molecular formula, same structural formula but different behaviour towards PPL (plane polarised light). The actual three dimensional arrangement of groups in a molecule containing asymmetric carbon is termed as absolute configuration. Conformational Isomerism : The different arrangement of atoms in space that result from the free rotation around single bond, are called conformations. The phenomenon is called conformational isomerism.
MCQ on Isomerism Pdf for NEET
Question 1: Which of the following is not a metamer of C⁴H¹⁰O________
A) Diethyl ether
B) Methyl n-propyl ether
C) 2–Methoxy propane
D) Isobutyl alcohol
Answer: D) Isobutyl alcohol
Explanation: Isobutyl alcohol is an alcohol, not an ether; metamers have the same functional group but different alkyl groups on either side, like in ethers.
Question 2: The number of stereo isomers of glucose (a six carbon sugar) is________
A) 8
B) 12
C) 16
D) 24
Answer: C) 16
Explanation: Glucose has 4 chiral centers, so it has 2⁴ = 16 stereoisomers.
Question 3: Which similarity is necessary for isomerism______
A) Molecular formula
B) Structure formula
C) Physical formula
D) Chemical formula
Answer: A) Molecular formula
Explanation: Isomers have the same molecular formula but different structures or arrangements.
Question 4: Number of structural isomers of C₆H₁₄ is________
A) 3
B) 4
C) 5
D) 6
Answer: C) 5
Explanation: C₆H₁₄ (hexane) has 5 structural isomers due to different branching of carbon chains.
Question 5: How many isomers of C⁵H¹¹OH will be primary alcohols (exclude stereoisomers)______
A) 2
B) 3
C) 4
D) 6
Answer: C) 4
Explanation: Four structural isomers of C₅H₁₁OH have the –OH group on a primary carbon atom.
Question 6: The minimum number of carbon atoms present in an organic compound to show chain isomerism is_________
A) 2
B) 3
C) 5
D) 4
Answer: D) 4
Explanation: Chain isomerism appears when compounds have at least 4 carbon atoms allowing branching.
Question 7: The minimum number of carbon atoms present in an organic compound to be able to show position isomerism is_______
A) 3
B) 4
C) 2
D) 5
Answer: C) 2
Explanation: Compounds with 2 carbon atoms can show position isomerism, such as alcohols with different –OH positions.
Question 8: Which of the following compounds will exhibit cis-trans (geometrical) isomerism ?
A) 1-Butanol
B) 2-Butene
C) 2-Butanol
D) 2-Butyne
Answer: B) 2-Butene
Explanation: 2-Butene has a double bond between two middle carbon atoms, allowing cis-trans arrangement.
Question 9: The minimum number of carbon atoms in ketone to show metamerism_______
A) 3
B) 4
C) 5
D) 6
Answer: C) 5
Explanation: Metamerism in ketones starts from 5 carbon atoms, allowing different alkyl groups on both sides of the carbonyl group.
Question 10: Which of the following show Geometrical isomerism________
A) 1,1–Diphenyl–1–butene
B) 1,1–Diphenyl–2–butene
C) 2,3–Dimethyl–2–butene
D) 3-Phenyl–1–butene
Answer: B) 1,1–Diphenyl–2–butene
Explanation: This compound has restricted rotation around the double bond with two different groups on each carbon, enabling cis-trans forms.
Question 11: Which of the following does not contain any asymmetric carbon but can show enantiomerism_______
A) Lactic acid
B) 1,3-pentadiene
C) Tartaric acid
D) 2,3-pentadiene
Answer: D) 2,3-pentadiene
Explanation: 2,3-Pentadiene is an example of axial chirality and can show enantiomerism without a chiral center.
Question 12: Find the number of stereo isomers of 1,2-dihydroxy cyclopentane_________
A) 1
B) 2
C) 3
D) 4
Answer: C) 3
Explanation: It has two chiral centers, giving 4 isomers, but one is a meso compound, so 3 stereoisomers exist.
Question 13: Which of the following acids does not exhibit optical isomerism?
A) Lactic acid
B) Tartaric acid
C) Maleic acid
D) α-amino acids
Answer: C) Maleic acid
Explanation: Maleic acid has no chiral carbon, so it cannot show optical isomerism.
Question 14: Two possible stereo-structures of CH₃CHOH.COOH, which are optically active, are called________
A) Enantiomers
B) Mesomers
C) Diastereomers
D) Atropisomers
Answer: A) Enantiomers
Explanation: These are mirror images that are non-superimposable due to a single chiral center.
Question 15: The number of structural isomers possible from the molecular formula C₃H₉N is_________
A) 2
B) 3
C) 4
D) 5
Answer: B) 3
Explanation: C₃H₉N has 3 structural isomers including primary, secondary, and tertiary amines.
Question 16: The simplest alkanol exhibiting optical activity is_____________
A) n-butyl alcohol
B) Isobutyl alcohol
C) s-butyl alcohol
D) t-butyl alcohol
Answer: C) s-butyl alcohol
Explanation: s-Butyl alcohol has a chiral carbon, making it optically active.
Question 17: Which of the following statement is incorrect?
A) It is possible to separate eclipsed and staggered form of ethane at room temperature.
B) Eclipsed form has torsional strain.
C) Ethane has infinite number of conformers.
D) Energy difference between staggered form and eclipsed form of ethane is 12.5 kJ/mole.
Answer: A) It is possible to separate eclipsed and staggered form of ethane at room temperature.
Explanation: The energy barrier is too low to separate conformers at room temperature.
Question 18: With respect to the conformers of ethane, which of the following statements is true?
A) Bond angle changes but bond length remains same
B) Both bond angle and bond length change
C) Both bond angles and bond length remains same
D) Bond angle remains same but bond length changes
Answer: C) Both bond angles and bond length remains same
Explanation: Conformers differ in spatial arrangement due to rotation but bond angles and lengths stay the same.
Question 19: The correct statement regarding the comparison of staggered and eclipsed conformation of ethane, is___________
A) The staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain
B) The eclipsed conformation of ethane is more stable than staggered conformation, because eclipsed conformation has no torsional strain
C) The eclipsed conformation of ethane is more stable than staggered conformation even though the eclipsed conformation has torsional strain
D) The staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.
Answer: D) The staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.
Explanation: Staggered form is more stable as there is less repulsion between electron clouds of adjacent bonds.
Question 20: Rotational angle required to get maximum stable conformer from minimum stable conformer in n-butane is_____________
A) 360°
B) 180°
C) 120°
D) 240°
Answer: B) 180°
Explanation: Maximum stability (anti-form) is obtained when the two bulky groups are 180° apart.
Question 21: Which conformation of butane will have the minimum energy__________
A) Gauche
B) Anti/staggered
C) Eclipsed
D) None
Answer: B) Anti/staggered
Explanation: Anti conformation has the least torsional and steric strain, making it the lowest energy conformation.
MCQ on Isomerism :
Practicing these MCQ on Isomerism for class 11 will help you to answer every question that is being asked in the board exams as well as in NEET Exam also. Students can solve these Isomerism MCQ for NEET Pdf Download to know their preparation level. Isomerism Objective type Questions help the students to understand the concepts thoroughly and to score good marks in NEET. The below Multiple Choice Questions on Isomerism with answers Pdf have been prepared as per the latest syllabus. Practice it now and score high in NEET exam.
Important Points to Remember about Isomerism:
- Two or more than two compounds having the same molecular formula but different physical/chemical or both properties are called isomers and the phenomenon is called isomerism.
- Chain Isomerism (C.I.) : The compounds which have same molecular formula, same functional group but different arrangement of carbon chain (Parental or side chain) show chain isomerism.
- Position Isomerism (P.I.) : The compounds which have same molecular formula, same functional group, same parent carbon chain but different position of functional group or multiple bond or substituents, show position isomerism.
- Functional Isomerism : Same molecular formula but different functional groups.
- Metamerism : Same molecular formula, same polyvalent Functional group but different alkyl groups attached to polyvalent Functional group.
- Stereo Isomerism : Two or more than two compounds having same molecular formula, same structural formula but different arrangements of atoms or groups in space.
- Optical isomers : Two or more than two compound have same molecular formula, same structural formula but different behaviour towards PPL (plane polarised light).
- The actual three dimensional arrangement of groups in a molecule containing asymmetric carbon is termed as absolute configuration.
- Conformational Isomerism : The different arrangement of atoms in space that result from the free rotation around single bond, are called conformations. The phenomenon is called conformational isomerism.
MCQ on Isomerism for NEET Pdf :
1. Which of the following is not a metamer of C⁴H¹⁰O________
(1) Diethyl ether
(2) Methyl n-propyl ether
(3) 2–Methoxy propane
(4) Isobutyl alcohol
Answer: 4
2. The number of stereo isomers of glucose (a six carbon sugar) is________
(1) 8
(2) 12
(3) 16
(4) 24
Answer: 3
3. Which similarity is necessary for isomerism______
(1) Molecular formula
(2) Structure formula
(3) Physical formula
(4) Chemical formula
Answer: 1
4. Number of structural isomers of C6H14 is________
(1) 3
(2) 4
(3) 5
(4) 6
Answer :3
5. How many isomers of C⁵H¹¹OH will be primary alcohols (exclude stereoisomers)______
(1) 2
(2) 3
(3) 4
(4) 6
Answer: 3
6. The minimum number of carbon atoms present in an organic compound to show chain isomerism is_________
(1) 2
(2) 3
(3) 5
(4) 4
Answer: 4
7. The minimum number of carbon atoms present in an organic compound to be able to show position isomerism is_______
(1) 3
(2) 4
(3) 2
(4) 5
Answer: 3
8. Which of the following compounds will exhibit cis-trans (geometrical) isomerism ?
(1) 1-Butanol
(2) 2-Butene
(3) 2-Butanol
(4) 2-Butyne
Answer: 2
9. The minimum number of carbon atoms in ketone to show metamerism_______
(1) 3
(2) 4
(3) 5
(4) 6
Answer: 3
10. Which of the following show Geometrical isomerism________
(1) 1,1–Diphenyl–1–butene
(2) 1,1–Diphenyl–2–butene
(3) 2,3–Dimethyl–2–butene
(4) 3-Phenyl–1–butene
Answer : 2
11. Which of the following does not contain any asymmetric carbon but can show enantiomerism_______
(1) Lactic acid
(2) 1,3-pentadiene
(3) Tartaric acid
(4) 2,3-pentadiene
Answer: 4
12. Find the number of stereo isomers of 1,2-dihydroxy cyclopentane_________
(1) 1
(2) 2
(3) 3
(4) 4
Answer: 3
13. Which of the following acids does not exhibit optical isomerism?
(1) Lactic acid
(2) Tartaric acid
(3) Maleic acid
(4) a-amino acids
Answer: 3
14. Two possible stereo-structures of
CH³CHOH.COOH, which are optically active, are called________
(1) Enantiomers
(2) Mesomers
(3) Diastereomers
(4) Atropisomers
Answer: 1
15. The number of structural isomers possible from the molecular formula C³H⁹N is_________
(1) 2
(2) 3
(3) 4
(4) 5
Answer: 3
16. The simplest alkanol exhibiting optical activity is_____________
(1) n-butyl alcohol
(2) Isobutyl alcohol
(3) s-butyl alcohol
(4) t-butyl alcohol
Answer: 3
17. Which of the following statement is incorrect?
(1) It is possible to separate eclipsed and staggered
form of ethane at room temprature.
(2) Eclipsed form has torsional strain.
(3) Ethane has infinite number of confomer.
(4) Energy difference between staggered form and eclipsed form of ethane is 12.5 kJ/mole.
Answer: 1
18. With respect to the conformers of ethane, which of the following statements is true ?
(1) Bond angle changes but bond length remains same
(2) Both bond angle and bond length change
(3) Both bond angles and bond length remains same
(4) Bond angle remains same but bond length changes
Answer: 3
19. The correct statement regarding the comparison of staggered and eclipsed conformation of ethane, is___________
(1) The staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain
(2) The eclipsed conformation of ethane is more stable than staggered conformation, because eclipsed conformation has no torsional strain
(3) The eclipsed conformation of ethane is more stable than staggered conformation even through the eclipsed conformation has torsional strain
(4) The staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.
Answer: 4
20. Rotational angle require to get maximum stable conformer from minimum stable conformer in n-butane is_____________
(1) 360°
(2) 180°
(3) 120°
(4) 240°
Answer: 2
21. Which conformation of butane will have the minimum energy__________
(1) Gauche
(2) Anti/staggered
(3) Eclipsed
(4) None
Answer: 2