Class 11 Chemistry Chapter 8 MCQs

1. Who synthesised urea from ammonium cyanate in 1828, disproving the ‘vital force’ theory?

(A) Berzilius

(B) F. Wohler

(D) Berthelot

Answer

Answer: (B) F. Wohler

2. Which element possesses the unique property of catenation to form covalent bonds with other atoms of itself?

(A) Oxygen

(B) Nitrogen

(D) Sulphur

Answer

Answer: (C) Carbon

3. What is the shape of a carbon atom with sp3 hybridisation?

(A) Linear

(B) Trigonal planar

(D) Octahedral

Answer

Answer: (C) Tetrahedral

4. The sp hybrid orbital possesses what percentage of s character?

(A) 25%

(B) 33%

(D) 75%

Answer

Answer: (C) 50%

5. How many sigma and pi bonds are present in ethyne (HC≡CH)?,

(A) 2 sigma, 2 pi

(B) 3 sigma, 2 pi

(D) 2 sigma, 3 pi

Answer

Answer: (B) 3 sigma, 2 pi

6. In bond-line structural representations of organic molecules, carbon and hydrogen atoms are generally:

(A) Explicitly written

(B) Represented by dots

(D) Represented by circles

Answer

Answer: (C) Not shown

7. In the 3-D representation of organic molecules, the solid-wedge indicates:

(A) A bond projecting away from the observer

(B) A bond in the plane of the paper

(D) A delocalised bond

Answer

Answer: (C) A bond projecting out of the plane towards the observer

8. Organic compounds consisting of straight or branched carbon chains are called:

(A) Alicyclic compounds

(B) Acyclic or aliphatic compounds

(D) Heterocyclic compounds

Answer

Answer: (B) Acyclic or aliphatic compounds

9. Tetrahydrofuran is an example of which type of ring compound?

(A) Benzenoid aromatic

(B) Alicyclic

(D) Heterocyclic

Answer

Answer: (D) Heterocyclic

10. The successive members of a homologous series differ from each other by which unit?

(A) -CH

(B) -CH2

(D) -OH

Answer

Answer: (B) -CH2

11. Which of the following functional groups has the highest priority in IUPAC nomenclature?

(A) -OH

(B) -CHO

(D) -COOH

Answer

Answer: (D) -COOH

12. What is the accepted common name for methoxybenzene?

(A) Toluene

(B) Aniline

(D) Phenol

Answer

Answer: (C) Anisole

13. Isomerism arising due to different alkyl chains on either side of the functional group is termed:

(A) Position isomerism

(B) Functional group isomerism

(D) Chain isomerism

Answer

Answer: (C) Metamerism

14. Heterolytic cleavage of a covalent bond generally results in the formation of:

(A) Free radicals

(B) Carbocations and carbanions

(D) Isotopes

Answer

Answer: (B) Carbocations and carbanions

15. Which of the following carbocations is the most stable?

(A) Methyl cation

(B) Primary carbocation

(D) Tertiary carbocation

Answer

Answer: (D) Tertiary carbocation

16. The carbon atom in a methyl carbocation is:

(A) sp3 hybridised

(B) sp2 hybridised

(D) unhybridised

Answer

Answer: (B) sp2 hybridised

17. Homolytic cleavage of a covalent bond is indicated by which type of arrow?

(A) Double-headed arrow

(B) Straight arrow

(D) Dashed arrow

Answer

Answer: (C) Half-headed (fish hook) curved arrow

18. A reagent that brings an electron pair to a reactive site is called a:

(A) Nucleophile

(B) Electrophile

(D) Carbocation

Answer

Answer: (A) Nucleophile

19. Which of the following acts as an electrophile?

(A) H2O

(B) NH3

(D) OH-

Answer

Answer: (C) BF3

20. The permanent polarisation of a sigma-bond caused by an adjacent polar bond is known as:

(A) Electromeric effect

(B) Resonance effect

(D) Inductive effect

Answer

Answer: (D) Inductive effect

21. Which of the following groups shows an electron-withdrawing (-I) effect?

(A) -CH3

(B) -CH2CH3

(D) -CH(CH3)2

Answer

Answer: (C) -NO2

22. The uniform C-C bond distance in benzene, intermediate between single and double bonds, is:

(A) 154 pm

(B) 134 pm

(D) 120 pm

Answer

Answer: (C) 139 pm

23. Which electronic effect is temporary and operates only in the presence of an attacking reagent?

(A) Inductive effect

(B) Electromeric effect

(D) Resonance effect

Answer

Answer: (B) Electromeric effect

24. Delocalisation of sigma electrons of a C-H bond into an adjacent empty p-orbital or unsaturated system is called:

(A) Hyperconjugation

(B) Resonance

(D) Electromeric effect

Answer

Answer: (A) Hyperconjugation

25. Which purification technique is used to separate sublimable compounds from non-sublimable impurities?

(A) Crystallisation

(B) Distillation

(D) Sublimation

Answer

Answer: (D) Sublimation

26. Crystallisation is based on the difference in which property of the compound and its impurities?

(A) Boiling point

(B) Density

(D) Vapour pressure

Answer

Answer: (C) Solubilities

27. Which distillation technique is used to separate liquids having a very small difference in their boiling points?

(A) Simple distillation

(B) Fractional distillation

(D) Distillation under reduced pressure

Answer

Answer: (B) Fractional distillation

28. Distillation under reduced pressure is used to purify liquids that:

(A) Are immiscible in water

(B) Have very low boiling points

(D) Are steam volatile

Answer

Answer: (C) Decompose at or below their boiling points

29. Which technique is applied to separate substances that are steam volatile and immiscible with water?

(A) Differential extraction

(B) Fractional distillation

(D) Sublimation

Answer

Answer: (C) Steam distillation

30. Aniline is usually separated from an aniline-water mixture using:

(A) Steam distillation

(B) Simple distillation

(D) Sublimation

Answer

Answer: (A) Steam distillation

31. The technique based on continuous differential partitioning of components between a stationary and a mobile phase is called:

(A) Adsorption chromatography

(B) Partition chromatography

(D) Thin-layer chromatography

Answer

Answer: (B) Partition chromatography

32. Paper chromatography is a specific example of:

(A) Partition chromatography

(B) Adsorption chromatography

(D) Thin-layer chromatography

Answer

Answer: (A) Partition chromatography

33. In chromatography, the retardation factor (Rf) is the ratio of the distance moved by the substance to the distance moved by the:

(A) Stationary phase

(B) Impurities

(D) Adsorbent

Answer

Answer: (C) Solvent from base line

34. In Lassaigne’s test, elements in an organic compound are converted into ionic form by fusing the compound with:

(A) Potassium metal

(B) Magnesium metal

(D) Calcium metal

Answer

Answer: (C) Sodium metal

35. In Lassaigne’s test for nitrogen, the formation of which colour confirms the presence of nitrogen?

(A) Blood red

(B) Prussian blue

(D) White

Answer

Answer: (B) Prussian blue

36. In Lassaigne’s test, if both nitrogen and sulphur are present in the compound, which colour is formed upon reacting with iron(III) ions?

(A) Prussian blue

(B) Blood red

(D) Black

Answer

Answer: (B) Blood red

37. In the detection of halogens, a yellow precipitate insoluble in ammonium hydroxide indicates the presence of:,

(A) Chlorine

(B) Bromine

(D) Fluorine

Answer

Answer: (C) Iodine

38. During the test for phosphorus, a yellow precipitate is formed by heating the solution with nitric acid and adding which reagent?

(A) Silver nitrate

(B) Lead acetate

(D) Sodium nitroprusside

Answer

Answer: (C) Ammonium molybdate

39. In quantitative analysis, carbon and hydrogen are oxidised to carbon dioxide and water respectively using an excess of:

(A) Copper(II) oxide

(B) Silver nitrate

(D) Sodium peroxide

Answer

Answer: (A) Copper(II) oxide

40. In the Dumas method, nitrogen gas is estimated by collecting it over an aqueous solution of:

(A) Sodium hydroxide

(B) Potassium hydroxide

(D) Barium hydroxide

Answer

Answer: (B) Potassium hydroxide

41. In Kjeldahl’s method, the nitrogen present in the organic compound is converted into:

(A) Nitrogen gas

(B) Sodium cyanide

(D) Nitric acid

Answer

Answer: (C) Ammonium sulphate

42. Kjeldahl’s method is NOT applicable for compounds containing nitrogen in which of the following forms?

(A) Amines

(B) Amides

(D) Amino acids

Answer

Answer: (C) Nitro and azo groups

43. The Carius method is commonly used for the quantitative estimation of:,

(A) Carbon and Hydrogen

(B) Halogens and Sulphur

(D) Oxygen

Answer

Answer: (B) Halogens and Sulphur

44. In the estimation of sulphur by the Carius method, sulphur is precipitated and weighed as:

(A) Lead sulphide

(B) Copper sulphide

(D) Silver sulphide

Answer

Answer: (C) Barium sulphate

45. In the direct quantitative estimation of oxygen, carbon monoxide formed is oxidised to carbon dioxide using:

(A) Copper(II) oxide

(B) Iodine pentoxide

(D) Sodium peroxide

Answer

Answer: (B) Iodine pentoxide

46. Which of the following electronic effects is a permanent electron displacement effect?

(A) Electromeric effect

(B) Inductive effect

(D) Polarisability effect

Answer

Answer: (B) Inductive effect

47. The carbon atom in a carbanion is generally in which hybridization state?

(A) sp

(B) sp2

(D) unhybridised

Answer

Answer: (C) sp3

48. The branched structural unit -CH2C(CH3)3 is commonly known as which group?

(A) Isobutyl

(B) sec-Butyl

(D) tert-Butyl

Answer

Answer: (C) Neopentyl

49. Which of the following is considered an acyclic (open chain) compound?,

(A) Cyclohexane

(B) Isobutane

(D) Tetrahydrofuran

Answer

Answer: (B) Isobutane

50. Compounds having the same molecular formula but differing in the position of a substituent or functional group are called:

(A) Chain isomers

(B) Functional group isomers

(D) Metamers

Answer

Answer: (C) Position isomers