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Chemistry of Hydrocarbons Online Mcqs Test

Mustansar KhanLast Updated: October 14, 2025

Important Chemistry Transition Elements Question and Answer

Total Questions:	49
Time Allowed:	30 Minutes
Total Marks:	49
How to Attempt Test:	Please choose the right Option in MCQ-type question.
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Chemistry Transition Elements Practice Test Online With Explanation

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1. How many π bonds are there in benzene?

2. Which of the following is formed during nitration of benzene?

Phenol

Benzaldehyde

Nitrobenzene

Toluene

3. The resonance structure of benzene was proposed by:

Kekulé

Mendeleev

Lewis

Dalton

4. Which hydrocarbon burns with a sooty flame?

Propane

Ethene

Ethane

Benzene

5. Which compound is used as a test for unsaturation?

NaCl

Br₂ (in CCl₄)

HCl

AgNO₃

6. Which of the following describes the MO model of benzene?

π electrons localized

π electrons in separate orbitals

Delocalized π molecular orbitals

Alternating bonds

7. What is the hybridization of carbon atoms in alkanes?

dsp²

sp³

sp²

8. What is the bond angle in benzene?

60°

109.5°

120°

90°

9. How many sigma bonds are there in benzene?

10. The reaction of benzene with Cl₂ in the presence of FeCl₃ is called:

Electrophilic substitution

Oxidation

Hydrolysis

Chlorination

11. What is the general formula of alkanes?

CnH2n+1

CnH2n–2

CnH2n+2

CnH2n

12. Which condition favors the halogenation of benzene?

Dilute acid

Basic medium

Presence of Lewis acid catalyst

UV light only

13. Which of the following hydrocarbons has the highest degree of unsaturation?

Ethane

Benzene

Butane

Methane

14. Which of the following is an isomer of butene?

Cyclobutane

Methylpropene

Ethane

Butane

15. Which of the following is a positional isomer of but-1-ene?

Cyclobutane

But-2-ene

Ethene

Isobutane

16. Which reaction is typical of alkenes?

Addition

Elimination

Substitution

Combustion only

17. Which of the following is an open-chain hydrocarbon?

Cyclohexane

Cyclopropane

Ethane

Benzene

18. What is the IUPAC name of CH₃–CH₂–CH₃?

Propane

Ethane

Methane

Butane

19. What is the product when benzene is treated with conc. HNO₃ and conc. H₂SO₄?

Benzaldehyde

Benzene sulfonic acid

Phenol

Nitrobenzene

20. Which of the following is not an aromatic compound?

Benzene

Toluene

Naphthalene

Cyclohexane

21. What type of hybridization is present in benzene?

None

sp³

sp²

22. What is the result of sulfonation of benzene?

Nitrobenzene

Phenol

Benzyl chloride

Benzene sulfonic acid

23. Which of the following is a closed-chain hydrocarbon?

Cyclobutane

Ethene

Propane

Butane

24. Benzene is best described as:

A cycloalkane

A saturated hydrocarbon

An aromatic compound

An alkene

25. Which of the following is a reaction of alkynes?

Elimination

Hydrolysis

Hydrogenation

Substitution

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26. Which of the following is the correct name for CH₂=CH–CH₃?

Propane

Butene

Propyne

Propene

27. What is the role of FeCl₃ in benzene chlorination?

Oxidizing agent

Base

Catalyst

Reducing agent

28. Which compound will give a positive test with Baeyer's reagent?

Methane

Ethene

Ethane

Benzene

29. Which of the following is not a property of aromatic hydrocarbons?

Undergo substitution

High stability

High reactivity to addition

Delocalized electrons

30. Which of the following is an alkyne?

Butyne

Ethene

Propane

Butane

31. Which of the following best explains the stability of benzene?

Localized π bonds

High molecular weight

Resonance and delocalized electrons

Single and double bond alternation

32. Which type of orbital overlap forms the π bonds in benzene?

s-s head-on

p-p sideways

sp²-sp²

sp-sp

33. Which of the following hydrocarbons is saturated?

Ethene

Ethyne

Butyne

Propane

34. Which of the following alkanes has a branched structure?

Ethane

Propane

Butane

Isobutane

35. Which of the following shows aromatic behavior?

Cyclohexene

Cyclopentadiene

Cyclobutadiene

Benzene

36. What is the molecular formula of benzene?

C₆H₁₀

C₆H₁₂

C₆H₆

C₅H₁₀

37. What is the IUPAC name of CH≡C–CH₃?

Propene

Propyne

Butyne

Propane

38. How many π electrons are present in benzene?

39. Which functional group is present in alkenes?

C=C

C≡C

–OH

–COOH

40. The stability of benzene is explained by:

Localized bonding

Delocalization of pi electrons

Single and double bonds

Carbon-carbon single bonds only

41. Which reagent is used for bromination of benzene?

HBr

Br₂/UV

Br₂/FeBr₃

Br₂ only

42. What kind of bonding exists in the benzene ring?

Sigma and delocalized pi bonds

Only pi bonds

Only sigma bonds

Double and single alternating bonds

43. Which of the following is an example of an electrophilic substitution reaction?

Hydrolysis of ester

Nitration of benzene

Combustion of alkane

Addition of HBr to ethene

44. Why does benzene not decolorize bromine water?

It is saturated

It forms addition products

It reduces bromine

It undergoes substitution instead

45. Which of the following reactions is characteristic of benzene?

Substitution

Polymerization

Addition

Hydrolysis

46. What is the outcome when benzene reacts with CH₃Cl in the presence of AlCl₃?

Benzyl chloride

Benzaldehyde

Chlorobenzene

Toluene

47. Which of the following is not a valid resonance structure of benzene?

Structure with unpaired electrons

Structure with delocalized electrons

Kekulé structures

Structure with alternating double bonds

48. What is the shape of the benzene molecule?

Tetrahedral

Hexagonal planar

Square

Linear

49. Which rule is used to determine aromaticity in compounds like benzene?

Hund’s rule

Avogadro's law

Huckel’s rule

Pauli exclusion principle

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Mustansar KhanLast Updated: October 14, 2025

Chemistry of Hydrocarbons Online Mcqs Test

Important Chemistry Transition Elements Question and Answer

Chemistry Transition Elements Practice Test Online With Explanation

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