Class 11 Chemistry Chapter 9 Hydrocarbon

1. What does the term ‘hydrocarbon’ mean?

(A) Compounds of carbon and oxygen only

(B) Compounds of carbon and hydrogen only

(D) Compounds of carbon, hydrogen, and oxygen

Answer

Answer: (B) Compounds of carbon and hydrogen only

2. What is the full form of LPG?

(A) Light Petroleum Gas

(B) Liquified Petrochemical Gas

(D) Liquid Propane Gas

Answer

Answer: (C) Liquified Petroleum Gas

3. What is the general formula for alkanes?

(A) CnH2n

(B) CnH2n-2

(D) CnH2n+1

Answer

Answer: (C) CnH2n+2

4. According to VSEPR theory, what is the structure of methane?

(A) Linear

(B) Trigonal planar

(D) Octahedral

Answer

Answer: (C) Tetrahedral

5. What is the H-C-H bond angle in methane?

(A) 90°

(B) 109.5°

(D) 180°

Answer

Answer: (B) 109.5°

6. What is the C-C bond length in alkanes?

(A) 112 pm

(B) 120 pm

(D) 154 pm

Answer

Answer: (D) 154 pm

7. What were alkanes earlier known as due to their unreactive nature under normal conditions?

(A) Olefins

(B) Paraffins

(D) Halides

Answer

Answer: (B) Paraffins

8. How many structural isomers are possible for C4H10 (butane)?

(A) 2

(B) 3

(D) 5

Answer

Answer: (A) 2

9. How many chain isomers are possible for C5H12 (pentane)?

(A) 2

(B) 3

(D) 5

Answer

Answer: (B) 3

10. Which process involves the addition of dihydrogen gas to alkenes or alkynes in the presence of catalysts?

(A) Halogenation

(B) Hydrogenation

(D) Hydrolysis

Answer

Answer: (B) Hydrogenation

11. Which metal is used in the Wurtz reaction to prepare higher alkanes?

(A) Zinc

(B) Magnesium

(D) Calcium

Answer

Answer: (C) Sodium

12. What is the process of elimination of carbon dioxide from a carboxylic acid known as?

(A) Dehydrogenation

(B) Decarboxylation

(D) Sulphonation

Answer

Answer: (B) Decarboxylation

13. Which specific alkane cannot be prepared by Kolbe’s electrolytic method?

(A) Ethane

(B) Propane

(D) Butane

Answer

Answer: (C) Methane

14. What is the physical state of the first four members of alkanes (C1 to C4) at 298 K?

(A) Gases

(B) Liquids

(D) Plasma

Answer

Answer: (A) Gases

15. What is the correct order for the rate of reaction of alkanes with halogens?

(A) I2 > Br2 > Cl2 > F2

(B) F2 > Cl2 > Br2 > I2

(D) Br2 > Cl2 > F2 > I2

Answer

Answer: (B) F2 > Cl2 > Br2 > I2

16. What is the first step in the free radical chain mechanism of halogenation?

(A) Propagation

(B) Termination

(D) Elimination

Answer

Answer: (C) Initiation

17. What byproduct is formed during the incomplete combustion of alkanes with insufficient oxygen?

(A) Carbon monoxide

(B) Carbon black

(D) Methane

Answer

Answer: (B) Carbon black

18. What is the principal product when methane is oxidized with O2 in the presence of Cu at 523K and 100 atm?

(A) Methanal

(B) Methanol

(D) Carbon dioxide

Answer

Answer: (B) Methanol

19. Heating n-alkanes in the presence of anhydrous AlCl3 and HCl gas causes what type of reaction?

(A) Aromatization

(B) Combustion

(D) Pyrolysis

Answer

Answer: (C) Isomerisation

20. Which process converts n-hexane to benzene when heated to 773K with vanadium oxides?

(A) Aromatization

(B) Polymerization

(D) Decarboxylation

Answer

Answer: (A) Aromatization

21. What is the decomposition reaction of higher alkanes into smaller fragments by the application of heat called?

(A) Hydrolysis

(B) Pyrolysis

(D) Ozonolysis

Answer

Answer: (B) Pyrolysis

22. Which conformation of ethane has the minimum repulsive forces and maximum stability?

(A) Eclipsed

(B) Skew

(D) Boat

Answer

Answer: (C) Staggered

23. What is the general formula for alkenes?

(A) CnH2n+2

(B) CnH2n

(D) CnH2n+1

Answer

Answer: (B) CnH2n

24. What is the bond length of a C=C double bond in alkenes?

(A) 154 pm

(B) 120 pm

(D) 112 pm

Answer

Answer: (C) 134 pm

25. What kind of structural isomerism do but-1-ene and but-2-ene exhibit?

(A) Chain isomerism

(B) Position isomerism

(D) Optical isomerism

Answer

Answer: (B) Position isomerism

26. Which geometrical isomer has two identical atoms or groups located on the same side of the double bond?

(A) Trans isomer

(B) Cis isomer

(D) Para isomer

Answer

Answer: (B) Cis isomer

27. What is Lindlar’s catalyst primarily used for?

(A) Converting alkenes to alkanes

(B) Converting alkynes to cis-alkenes

(D) Converting alkynes to alkanes

Answer

Answer: (B) Converting alkynes to cis-alkenes

28. What does the reduction of alkynes with sodium in liquid ammonia predominantly produce?

(A) Alkanes

(B) Cis-alkenes

(D) Alcohols

Answer

Answer: (C) Trans-alkenes

29. The reaction of alkyl halides with alcoholic potash to form alkenes is an example of what type of reaction?

(A) Addition

(B) Substitution

(D) Polymerization

Answer

Answer: (C) Beta-elimination

30. What do vicinal dihalides yield upon heating with zinc metal?

(A) Alkynes

(B) Alkenes

(D) Alcohols

Answer

Answer: (B) Alkenes

31. Heating alcohols with concentrated sulphuric acid to form alkenes and eliminate water is known as?

(A) Acidic dehydration

(B) Hydration

(D) Hydrogenation

Answer

Answer: (A) Acidic dehydration

32. What is the order of reactivity of hydrogen halides towards alkenes?

(A) HCl > HBr > HI

(B) HBr > HCl > HI

(D) HI > HCl > HBr

Answer

Answer: (C) HI > HBr > HCl

33. According to Markovnikov’s rule, to which carbon does the negative part of the adding molecule attach?

(A) The carbon atom with more hydrogen atoms

(B) The carbon atom with fewer hydrogen atoms

(D) The last carbon atom of the chain

Answer

Answer: (B) The carbon atom with fewer hydrogen atoms

34. What is the major product of adding HBr to propene in the presence of peroxide?

(A) 2-Bromopropane

(B) 1-Bromopropane

(D) Propane

Answer

Answer: (B) 1-Bromopropane

35. What is a dilute aqueous solution of potassium permanganate commonly called in the context of testing unsaturation?

(A) Tollens’ reagent

(B) Fehling’s solution

(D) Grignard reagent

Answer

Answer: (C) Baeyer’s reagent

36. Which reaction is highly useful in detecting the exact position of a double bond in alkenes?

(A) Hydrogenation

(B) Polymerisation

(D) Combustion

Answer

Answer: (C) Ozonolysis

37. What is the general formula for alkynes?

(A) CnH2n

(B) CnH2n-2

(D) CnH2n-4

Answer

Answer: (B) CnH2n-2

38. What is the H-C-C bond angle in an ethyne molecule?

(A) 109.5°

(B) 120°

(D) 90°

Answer

Answer: (C) 180°

39. What is the carbon-carbon triple bond (C≡C) length in ethyne?

(A) 154 pm

(B) 134 pm

(D) 112 pm

Answer

Answer: (C) 120 pm

40. What gas is formed industrially when calcium carbide is treated with water?

(A) Methane

(B) Ethene

(D) Propane

Answer

Answer: (C) Ethyne

41. Because of its 50% s-character, which carbon hybridization is considered the most electronegative?

(A) sp3

(B) sp2

(D) They are identically electronegative

Answer

Answer: (C) sp

42. What cyclic polymer is formed when ethyne is passed through a red hot iron tube at 873K?

(A) Polyacetylene

(B) Benzene

(D) Toluene

Answer

Answer: (B) Benzene

43. Who successfully isolated benzene for the first time in 1825?

(A) August Kekulé

(B) Michael Faraday

(D) M.S. Kharash

Answer

Answer: (B) Michael Faraday

44. Based on X-ray diffraction, what is the uniform C-C bond length across the benzene ring?

(A) 154 pm

(B) 134 pm

(D) 120 pm

Answer

Answer: (C) 139 pm

45. What rule for aromaticity specifies the necessary presence of (4n + 2) pi electrons?

(A) Markovnikov Rule

(B) Kharash Rule

(D) VSEPR Rule

Answer

Answer: (C) Hückel Rule

46. From what primary commercial source is benzene isolated?

(A) Petroleum

(B) Natural gas

(D) Wood

Answer

Answer: (C) Coal tar

47. Heating the sodium salt of benzoic acid with sodalime yields what main product?

(A) Phenol

(B) Benzene

(D) Cyclohexane

Answer

Answer: (B) Benzene

48. What reagent is used to reduce phenol into benzene by passing its vapours over heat?

(A) Copper turning

(B) Zinc dust

(D) Magnesium ribbon

Answer

Answer: (B) Zinc dust

49. Which type of reactions uniquely characterize the chemical properties of arenes?

(A) Electrophilic addition reactions

(B) Nucleophilic substitution reactions

(D) Free radical addition reactions

Answer

Answer: (C) Electrophilic substitution reactions

50. What serious health hazard is strongly associated with polynuclear hydrocarbons containing more than two fused benzene rings?

(A) Cardiovascular disease

(B) Asthma

(D) Diabetes

Answer

Answer: (C) Carcinogenicity

Class 11 Chemistry Chapter 9 Hydrocarbon