SaitechAI Interactive MCQ Test
Isomerism – 30 Questions
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1. Isomers are compounds which have:
Different molecular formula and same structure
Same molecular formula but different structure
Different molecular formula and different structure
Key: Same molecular formula but different structure
2. Chain isomerism arises due to:
Different arrangement of the carbon skeleton
Different functional groups
Different spatial arrangement around a double bond
Key: Different arrangement of the carbon skeleton
3. CH
3
–O–C
4
H
9
and C
2
H
5
–O–C
3
H
7
are examples of:
Metamers
Positional isomers
Chain isomers
Key: Metamers
4. Functional isomer of ethanol is:
Dimethyl ether
Propanol
Methanal
Key: Dimethyl ether
5. Geometrical isomerism is mainly shown by:
Alkenes
Alkynes
Saturated alkanes
Key: Alkenes
6. A carbon atom becomes chiral when it is attached to:
Four different groups
Two identical and two different groups
Three different groups
Key: Four different groups
7. Mirror-image, non-superimposable stereoisomers are called:
Enantiomers
Diastereomers
Conformers
Key: Enantiomers
8. Isomerism due to restricted rotation about a C=C bond is:
Geometrical isomerism
Chain isomerism
Functional isomerism
Key: Geometrical isomerism
9. Keto–enol interconversion is an example of:
Tautomerism
Resonance
Conformational isomerism
Key: Tautomerism
10. Staggered form of ethane is more stable than eclipsed form because:
Torsional strain is minimum
Angle strain is maximum
Hyperconjugation is absent
Key: Torsional strain is minimum
11. How many chain isomers are possible for C
4
H
10
?
2
3
4
Key: 2
12. How many positional isomers of C
3
H
8
O (alcohols) are possible?
2
1
3
Key: 2 (1-propanol and 2-propanol)
13. Which of the following pairs shows functional isomerism?
Aldehyde and ketone (C
3
H
6
O)
n-butane and isobutane
1-propanol and 2-propanol
Key: Aldehyde and ketone (C₃H₆O)
14. Two compounds with same functional group but different position of substituent are:
Chain isomers
Positional isomers
Metamers
Key: Positional isomers
15. Which of the following is optically active?
2-chlorobutane
2-chloropropane
n-butane
Key: 2-chlorobutane
16. Which of the following does
not
show geometrical isomerism?
2-butene
2-methylpropene
Maleic acid
Key: 2-methylpropene
17. Number of chiral centres in lactic acid (CH
3
–CH(OH)–COOH) is:
1
2
0
Key: 1
18. Relationship between meso-tartaric acid and (+)-tartaric acid is:
Enantiomers
Diastereomers
Identical
Key: Diastereomers
19. Number of geometrical isomers possible for 2-butene is:
2
3
4
Key: 2 (cis and trans)
20. Conformational isomers of ethane differ by:
Rotation about C–C single bond
Breaking and making bonds
Change in functional group
Key: Rotation about C–C single bond
21. Which of the following is
not
a type of stereoisomerism?
Optical isomerism
Geometrical isomerism
Chain isomerism
Key: Chain isomerism
22. A pair of tautomers must differ in:
Position of a proton and a double bond
Only position of electrons
Only position of a substituent
Key: Position of a proton and a double bond
23. Trans-2-butene is more stable than cis-2-butene because:
Steric repulsion between CH
3
groups is less
It has higher energy
It is optically active
Key: Steric repulsion between CH₃ groups is less
24. Which molecule has a plane of symmetry and is optically inactive?
meso-tartaric acid
(+)-lactic acid
(+)-2-butanol
Key: meso-tartaric acid
25. Dextrorotation of plane-polarised light is represented by:
+ sign
− sign
0
Key: + sign
26. Enantiomers have identical physical properties except:
Direction of rotation of plane-polarised light
Boiling point
Density
Key: Direction of rotation of plane-polarised light
27. Diastereomers differ in:
Most physical and chemical properties
Only optical rotation
Only molecular formula
Key: Most physical and chemical properties
28. A compound is chiral if:
Its mirror image is non-superimposable
It has a plane of symmetry
It has no stereocentres
Key: Its mirror image is non-superimposable
29. In E-configuration of an alkene, the higher priority groups are:
On opposite sides of the double bond
On the same side of the double bond
Directly attached to same carbon
Key: On opposite sides of the double bond
30. Configurational isomers:
Can be interconverted only by breaking bonds
Interconvert by free rotation
Have different molecular formula
Key: Can be interconverted only by breaking bonds
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