Class 11 MCQ Question of Organic Chemistry: Some Basic Principles and Techniques

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Class 11 Chemistry MCQ Question of Organic Chemistry: Some Basic Principles and Techniques with Answers?

Answer 1

 These MCQ Questions on Organic Chemistry: Some Basic Principles and Techniques Class 11 with answers clear for a speedy update of the Chapter in this manner assisting you with improving subject information. Solving the Class 11 MCQ Questions of Organic Chemistry: Some Basic Principles and Techniques can be of outrageous help as you will know about each and every one of the concepts. 

Organic Chemistry is the part of science managing the study of carbon-containing compounds. Natural mixtures are crucial to life. The genetic material, proteins, medicines, fuels are on the whole organic compounds.

Learn and practice the important multiple-choice questions and score well in examinations. It makes you feel confident in answering the question in the exam.

Practice MCQ Questions for class 11 Chemistry Chapter-Wise

1. If two compounds have the same empirical formula but different molecular formula they must have

(a) Different percentage composition
(b) Different molecular weight
(c) Same viscosity
(d) Same vapour density

2. Identify the chiral molecule among the following:

(a) Isopropyl alcohol
(b) 2-pentanol
(c) 1-bromo 3-butene
(d) Isobutyl alcohol

3. The displacement of electrons in a multiple bond in the presence of attacking reagent is called

(a) Inductive effect
(b) Electromeric effect
(c) Resonance
(d) Hyper conjugation

4. Which of the following cannot be represented by resonance structures?

(a) Dimethyl ether
(b) Nitrate anion
(c) Carboxylate anion
(d) Toluene

5. An organic compound which produces a bluish green coloured flame on heating in presence of copper is

(a) Chlorobenzene
(b) Benzaldehyde
(c) Aniline
(d) Benzoic acid

6. Insulin contains 3.4% sulphur. The minimum molecular weight of insulin is

(a) 350
(b) 470
(c) 560
(d) 940

7.59 g of an amide obtained from a carboxylic acid, RCOOH, liberated 17 g of ammonia upon heating with alkali. The acid is

(a) Formic Acid
(b) Acetic Acid
(c) Propionic Acid
(d) Benzoic Acid

8. In the Dumas method, the nitrogen present in organic compound gets converted to

(a) Sodium Cyanide
(b) Gaseoue Ammonia
(c) Dinitrogen Gas
(d) Ammonium Sulphate

9. Which one of the following conformations of cyclohexane is chiral?

(a) Twist boat
(b) Rigid
(c) Chair
(d) Boat

10. If there is no rotation of plane polarized light by a compound in a specific solvent, thought to be chiral, it may mean that

(a) The compound may be a racemic mixture
(b) The compound is certainly a chiral
(c) The compound is certainly meso
(d) There is no compound in the solvent

11. Which element is estimated by Carius method

(a) Carbon
(b) Hydrogen
(c) Halogen
(d) Nitrogen

12. Which of the following behaves both as a nucleophile and as an electrophile?

(a) CH₃C ≡ N
(b) CH₃OH
(c) CH₂ = CHCH₃
(d) CH₃NH₂

13. Which of the following scientist proposed that a ‘vital force’ was responsible for the formation of organic compounds?

(a) Berzilius
(b) Wohler
(c) Berthelot
(d) Kolbe

14. First organic compound to be synthesised was

(a) urea
(b) cane sugar
(c) methane
(d) acetic acid

15. The percentage of s- character of the hybrid orbitals in ethane, ethene and ethyne are respectively

(a) 25, 33, 50
(b) 50, 75, 100
(c) 25, 50, 75
(d) 10, 20, 40

16. Butanone is a four-carbon compound with the functional group –

(a) ketone
(b) carboxylic acid
(c) aldehyde
(d) alcohol

17. The compound which has one isopropyl group is

(a) 2- Methypentane
(b) 2, 2, 3- Trimethylpentane
(c) 2, 2 - Dimethylpentane
(d) 2, 2, 3, 3 - Tetramethylpentane

18. Which of the following statements is false for isopentane?

(a) It has a carbon which is not bonded to hydrogen
(b) It has one CH group
(c) It has one CH₂ group
(d) It has three CH₃ groups

19. The IUPAC name of neopentane is

(a) 2, 2-dimethylpropane
(b) 2, 2-dimethylbutane
(c) 2-methylpropane
(d) 2-methylbutane

20. Paper chromatography is an example of

(a) Partition chromatography
(b) Thin layer chromatography
(c) Column chromatography
(d) Adsorption chromatography

21. A tertiary butyl carbocation is more stable than a secondary butyl carbocation because-

(a) + R effect of -CH₃ groups 
(b) - R effect of -CH₃ groups 
(c) Hyperconjugation
(d) - I effect of -CH₃ groups

22. Assertion: Oils are purified by steam distillation. 

Reason: The compounds which decompose at their boiling points can purified by steam distillation.

(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
(b) If both Assertion and Reason are true but the reason is not the correct explanation of the Assertion
(c) If Assertion is true but Reason is false
(d) If both Assertion and Reason are false

23. The most suitable method of separation of 1:1 mixture of ortho and para-nitrophenols is

(a) sublimation
(b) chromatography
(c) crystallisation
(d) steam distillation

24. The incorrect statement among the following for a nucleophile is-

(a) Nucleophile is a Lewis acid
(b) Ammonia is a nucleophile
(c) Nucleophiles attack low electrons density sites
(d) Nucleophiles are not electron seeking

25. Among the following compounds the one that is most reactive towards electrophilic nitration is

(a) benzoic acid
(b) nitrobenzene
(c) toluene
(d) benzene

Answer 2

1. Answer: (b) Different molecular weight

Explanation: Compounds with same empirical formula but different molecular formula have same percentage composition of elements but different molecular weight.

2. Answer: (a) Isopropyl alcohol

Explanation: Chirality is the condition for a molecule to be optically active and here isobutyl alcohol is the only compound is optically active and hence it is the chiral molecule.

3. Answer: (b) Electromeric effect

Explanation: Electromeric effect involves the complete transfer of electrons of a multiple bond (double or triple bond) to one of the bonded atoms (usually more electronegative) in presence of an attacking reagent. This effect is temporary and takes place only in the presence of a reagent. As soon as the reagent is removed, the molecule reverts back to its original position.

4. Answer: (a) Dimethyl ether

Explanation: Ethers due to absence of delocalized pair of electrons do not show resonance.

5. Answer: (a) Chlorobenzene

Explanation: Halogen containing compounds(C₆H₅CI) When placed in a flame, the presence of halogen is revealed by a green to blue flame.

6. Answer: (d) 940

Explanation: For minimum molecular mass, insulin must have at least one sulphur atom in its one molecule

If it has 3.4 gS, the mol. mass = 100

If it has 32gS, the mol. mass 

= \(\frac{100\times32}{3.4}\)

= 941.176

7. Answer: (b) Acetic Acid

Explanation: RCONH₂ + NaOH → RCOONa + NH₃ 

As 1 mole of NH₃ is given by one mole of amide. Thus mol. mass of RCONH₂ is

A + 12 + 16 + 14 + 2 = 59 

A + 44 = 59

A = 59 - 44 

= 15

Hence alkyl group with mol. mass A = 15 is CH₃

8. Answer: (c) Dinitrogen Gas

Explanation: Dumas' method involves the determination of nitrogen content in the organic compound in the form of  nitrogen (N₂). Organic compound is oxidized with cupric oxide in an atmosphere of carbon dioxide which gives free nitrogen along-with carbon dioxide and water .

9. Answer: (a) Twist boat

Explanation: wist-boat conformation of cyclohexane is chiral. The twist-boat conformation i.e.has minimised transannular interaction between "flagpole" hydrogens and at the same time torsional strain between the pair of side carbons of the initial boat are also relieved. The symmetry of twist-boat is reduced and the molecule is chiral.

10. Answer: (a) The compound may be a racemic mixture

Explanation: The compounds in which asymmetric carbon atom is present, are called optically active, they rotate the plane of polarised light but the compounds which do not show optical activity inspite of the presence of chiral carbon atoms are called meso-compounds. The absence of optical activity in these compounds is due to the presence of a plane of symmetry in the molecule.

11. Answer: (c) Halogen

Explanation: Halogens is estimated by carius method. In this method, the compound is first heated in the presence of nitric acid and silver nitrate, which converts any halogens or sulphur present into their corresponding silver salt. This salt can then be collected, weighed, and the amount of halogen or sulphur calculated based on the amount of silver salt recovered.

12. Answer: (a) CH₃C ≡ N

Explanation:\(R-C^{\delta}=N^{\delta}\) : has electrophilic C-atom and nucleophilic N-atom.

13. Answer: (a) Berzilius

Explanation: Berzelius was a Swedish scientist who in 1815 proposed that organic compounds could only be produced by some special force which must be existing in a living organism and could not be prepared in a laboratory. This force was called vital force and this theory came to be known as vital force theory.

14. Answer: (a) urea

Explanation: The first organic compound synthesised in the laboratory from inorganic compounds was urea.

15. Answer: (a) 25, 33, 50

Explanation: The hybrid orbitals used for bonding in methane (sp³), ethene (sp²) and ethyne (sp) have 25, 33 and 50% s-character.

16. Answer: (a) ketone

Explanation: In organic chemistry, the word butane shows the presence of four carbons.Thus, we can conclude that the functional group present in the compound is ketone.

17. Answer: (a) 2- Methypentane

Explanation: 

18. Answer: (d) It has three CH₃ groups

Explanation: 

19. Answer: (a) 2, 2-dimethylpropane

Explanation: 

20. Answer: (a) Partition chromatography

Explanation: Paper chromatography is an example of partition chromatography in which liquid present in the pores of paper is stationary phase and some other liquid is movable phase.

21. Answer: (c) Hyperconjugation

Explanation: Due to more hyperconjugation, tertiary butyl carbocation is more stable than secondary butyl carbocations.

22. Answer: (c) If Assertion is true but Reason is false

Explanation: Steam distillation is carried out only when a solid or liquid is insoluble in water and volatile with steam but the impurities are non-volatile.

23. Answer: (d) steam distillation

Explanation: Steam distillation is the most suitable method of separation of 1:1 mixture of ortho and para nitrophenols as there is intramolecular H-bonds in ortho nitrophenol.

24. Answer: (a) Nucleophile is a Lewis acid

Explanation: Nucleophiles are electron rich species so act as Lewis base.

25. Answer: (c) toluene

Explanation: Presence of electron releasing group like, -R, -OH etc., increases the electron density at ortho /para position and hence makes the benzene ring more reactive at ortho/para position towards electrophile. On the other hand, electron with drawing group such as -COOH, -NO₂ etc., if present, reduces electron density and thus reduces the reactivity of benzene nucleus towards electrophile. 

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