NCERT Class 11 Chemistry Chapter 12 Organic Chemistry Basic Principles And Techniques Very Short Question And Answers

NCERT Solutions For Class 11 Chemistry Chapter 12 Organic Chemistry Basic Principles And Techniques Very Short Question And Answers

Question 1. Which property of carbon is responsible for forming straight chains, branched chains, or rings?
Answer: Catenation property of carbon.

Question 2. Wind are the reason fort the existence of a large number of organic compounds.
Answer:

Reasons are: 

1. Catenation property of carbon
2. Its tendency to combine with other non-metals and
3. Phenomenon of isomerism exhibited by carbon compounds.

Question 3. Find the number of <r -and ;r -boud(s) in the molecule: CH₃CH₂CH==CH—C = 
Answer: Number of σ -bonds = 13 and number of π-bonds = 3

Question 4. Predict the state of hybridization of the starred carbon atoms: 

1. H*C ≡ CCH₃

2. 

Answer:

1. sp
2. sp².

Question 5. What is the shape of the molecule: C₆H₆CN?
Answer: Planar.

Question 6. Give the shape of the molecule: HC ≡ C — C ≡CCl
Answer: Linear

Question 7. What is the state of hybridization of a carbon atom linked to two other atoms by two double bonds?
Answer: Sp -hybridization.

Question 8.  Arrange the following in order of increasing carbon-carbon bond length: ethane, ethylene, and acetylene.
Answer:

Acetylene (HC ≡ CH) < Ethylene (CH₂=CH₂) < Ethane (CH₃—CH₃).

Question 9. What will be the shape of a hydrocarbon molecule containing two sp² – & one sp³ -hybridized C-atom?
Answer: Three-dimensional.

Question 10.  Arrange in order of increasing bond dissociation enthalpy:  C_sp— C_sp  —C_sp³ – C_sp³ —, C_sp² —C_sp² 
Answer:

C_sp³ — C_sp³ < C_sp² — C_sp²  < C_sp— C_sp

Question  11. Arrange the starred C-atoms in the following compound in order of increasing s -character of their hybridization states:
¹C*H₃—²CH=³C*H—⁴CH=⁵*C=⁶CH—⁷CH₂—⁸CH₃
Answer:

C-1 <C-3<C-5.

Question  12. Which is the correct bond-line structural formula of CH₂=CH—C = CCH₂CH₃ ?

Answer:

No. 2 s the correct bond-line structural formula.

Question 13. Write the names of an alicyclic compound and a heterocyclic compound.
Answer:

Cyclohexane and pyridine, respectively.

Question 14. Give one example of each benzenoid and non-benzenoid aromatic compound.
Answer: Toluene  and Azulene

Question 15. Write down the IUPAC name of the compound represented by the swastika sign.
Answer: 3,3-diethyl pentane

Question 16. Which one is the correct name of an alkyne containing five carbon atoms? Pent-2-yne or Pent-3-yne
Answer: Pent-2-yne.

Question 17. Mention the name of the alkyl group that may be obtained by removal of one 2° H-atom from propane.
Answer:  Isopropyl.

Question 18. How many alkyl groups are expected to be obtained from CH₃CH₂CH₂CH(CH₃)CH₂CH₃ by the removal of different non-equivalent H -atoms?
Answer: Seven alkyl groups because there are seven types of non-equivalent H -atoms.

Question 19. Which of the following has no existence? 

1. 1° H – atom
2. 3° C -atom
3. 2° H -atom
4. 4°H -atom

Answer: 4°H-atom has no existence

Question 20. How many 4°C-atoms are there in 2,2.3,3- tetramethylbutane?
Answer:. The number of 4°C- atoms is 2.

Question 21. How many 3°H-atoms are there in 4-ethyl-2- methylhexan e?
Answer: The number of 3° H-atoms is 2.

Question 22. Write the bond-line structural formula of an alkane with five carbon atoms which has only primary hydrogen atoms.
Answer: Bond-line structure of the alkane:

Question 23. Give examples of two terminal functional groups.
Answer: . —COOH, — CHO

Question 24. How many univalent groups are expected to be obtained from toluene?
Answer: 4 univalent groups can be expected

Question 25. What are the primary suffixes used to write IUPAC names of CH₃CH₃, CH₂=CH_2, and HC ≡CH?
Answer: ‘anej ‘ene’ and ‘yne’ respectively.

Question 26. Give an example of a saturated hydrocarbon that can be represented by the general formula, C_nH_2n.
Answer: Cyclopentane

Question 27. How many 7r -bonds are there in 3-methylidene-l, 4- pentadiene?
Answer: The number of n -bonds is 3.

Question 28. Write the names of the alkyl group(s) that may be obtained from (CH₃)₄C.
Answer: Neopentyl or 2,2-dimethylpropyl.

Question 29. Write the IUPAC name of a hydrocarbon containing one sp, two sp² & two sp³ -hybridized C-atoms
Answer: Penta-2,3-diene or 3-methyIbuta-l,2-diene.

Question 30. How many alkyl groups are possible having the molecular formula, C₄H₉?
Answer: 4 different alkyl groups are possible.

Question 31. Which type of isomerism is exhibited by n-pentane and neopentane?
Answer: Chain isomerism.

Question 32. Write down the structure and the IUPAC name of the tautomer of butanal
Answer: CH₃CH₂CH=CH— OH (But-l-en-l-ol).

Question 33. How many structural isomers will be obtained by the displacement of two H-atoms of propane by two Cl- atoms? Write their structures.
Answer: Question 65. A compFour (ClCH₂CH₂CH,Cl, ClCH₂CHClCH₃ , Cl₂CHCH₂CH₃ and CH₃CCl₂CH₃).

Question 34. Write structures and names of two compounds which are position isomers as well as metamers
Answer:

Question  35. How are the two compounds, CH₂=CHCH₂CH₃ and related to each other?
Answer: These two compounds are ring-chain isomers.

Question 36. Which two of the following are geometrical isomers?

Answer: 2 and 4 are geometrical isomers.

Question 37. Which of the following compounds do not exhibit geometrical isomerism

1. 

2. PhCH=CHPh

3. Me2C=NOH

4. CH₂=CH—CH=CH —CH=CH₂

Answer:  1 and 3 do not exhibit geometrical isomerism

Question 38. Which of the given compounds are optically active?

Answer: 3 and 4 are optically active compounds

Question 39. Mention the type of the following reaction: Me₃CCH₂OH + HBr Me₂CBrCH₂CH₃ + H₂O
Answer: It is a substitution and rearrangement reaction.

Question 40. How many types of non-equivalent H-atoms are present in the given compound?

Answer: Two types of non-equivalent H-atoms are present

Question 41. In which of the given compounds, all the H-atoms are; equivalent?

Answer: 1 and 3

Question 42. Calculate the double bond equivalent (DBE) of the compound having the molecular formula, C₆H₈ Is the compound aromatic?
Answer: DBE = 3 ; The compound is not aromatic

Question 43. How many monobrow derivatives are possible for each of Ortho, meta, and para-xylene?
Answer: Three, four, and two respectively

Question 44. Arrange the following groups in order of decreasing strength of -I effect groups in order of decreasing — ⁺NR₃, —NO₂, —F, —CN.
Answer:  — ⁺NR₃ >NO₂>—CN >—F

Question 45. Arrange the following free radicals in the decreasing order of their stability:

Answer: 5 >4>1>2>3

Question 46. In which C—C bond of CH₃CH₂CH₂Br, the inductive effect is expected to be the least?
Answer: C-2 —C-3 bond.

Question 47. Arrange the following carbocations in increasing order of stability

Answer: 4<2<1<3

Question 48. Arrange the following compounds in increasing order of number of hypercoagulable hydrogen atoms:

Answer: 6<2<3<5 <4<1

Question 49. Arrange the following compounds in order of increasing bond dissociation enthalpy:

1. CH₃ — H
2. (CH₃)₂CH-H
3. (CH₃)₃C—H
4. CH₃CH₂ —H

Answer: 3<2<4<1

Question 50. Arrange the following in increasing order of stability:

Answer: 4<2<3<1< 5

Question 51. How can aniline be purified?
Answer: By steam distillation as well as vacuum distillation.

Question 52. How can glycerol be purified?
Answer: By distillation under reduced pressure.

Question 53. Suggest a method to separate a mixture of o-hydroxybenzaldehyde and p-hydroxybenzaldehyde.
Answer: Steam distillation.

Question 54. How will you separate a mixture of two solid pounds of different solubilities in the same solvent?
Answer: By fractional crystallization.

Question  55. An organic liquid decomposes below its boiling point. How can it be purified?
Answer: By distillation under reduced pressure.

Question 56. Which technique can be used to purify iodine-containing traces of common salt?
Answer: Sublimation.

Question 57. Suggest a method for the purification of a liquid containing non-volatile Impurities.
Answer: Simple distillation

Question 58. How can aniline (b.p. 184°C) be separated from petroleum ether (b.p. 40-60°C)?
Answer: By simple distillation

Question 59. Out of water and benzene, which can be used to purify benzoic acid containing naphthalene by fractional crystallization?
Answer: Water (because both are soluble in benzene).

Question 60. Give an example of a chromatographic technique in which both the mobile and stationary phases are liquids
Answer: Paper chromatography.

Question 61. Mention two distillation processes in which organic liquids boil at temperatures below their respective boiling points. 
Answer: Distillation under reduced pressure & steam distillation.

Question 62. Explain why the Lassaigne’s extract should not be prepared by using tap water.
Answer: Because tap water contains chloride ion (Cl )

Question 63. Give an example of a compound that does not contain halogen but gives Beilstein’s test
Answer:  Pyridine (C₆H₅N)

Question 64. In Carius’s method for estimation of phosphorus, the precipitate of which compound is finally obtained?
Answer: Ammonium phosphomolybdate [(NH₄)₃PO₄-12MoO₃] or magnesium pyrophosphate (Mg₂P₂O₇).

Question 65. Give an example of a nitrogenous organic compound to which Kjeldahl’s method for the estimation of nitrogen is not applicable.
Answer: Azobenzene (C₆H₅— N=N—C₆H₅)

Question 66. What is the C — C=C bond angle value in a benzene (C₆H₆) molecule?
Answer: 120°

Question 67.  What is the H — C = C bond angle value in an acetylene (C₂H₂) molecule?
Answer: 180°

Question 68.  Mention the state of hybridization of C and N-atoms in
Answer: sp, sp²

Question 69. Mention the state of hybridization of the carbon atoms present in the molecule, CH₃CH =C =CHCH₂CH₃.
Answer: sp, sp, sp, sp, sp, sp

Question 70.  Give the name of a simple organic molecule that has a cylindrical n -electron cloud.
Answer: Acetylene

Question 71.  Give an example of a molecule in which all atoms lie in the same plane.
Answer: CH₂=CH₂

Question 72.  Give an example of a molecule in which all the atoms lie in a straight line.
Answer: HC = CH

Question 73. Calculate the number of cr and n -bonds in the molecule, CH3CH=CH—C = C —CHO.
Answer: σ -bond:12, π -bonds

Question 74. What are the possible values of n if CH₂=(C)_n—CH₂ is a planar molecule?
Answer: n = 0,2,4, — etc

Question 75. What are the possible values of n if CH₂— (C)n_n=CH₂ is a non-planar molecule?
Answer: n = 1, 3, 5, etc.

Question 76. Write the structure of a hydrocarbon molecule that contains one 4° carbon atom.
Answer:  (CH₃)₄C;

Question 77. Give an example of a compound that contains primary (1°), secondary (2°), and tertiary (3°) H -atoms.
Answer: CH₃CH₂CH(CH₃)₂

Question 78. How many alkyl groups can be derived from the alkane, CH₃(CH₂)₃CH₃?
Answer: Three

Question 79.  Write the group prefix used for the — COOH group.
Answer: ‘oic acid’;

Question 80.  Write the IUPAC name:
Answer: (3-ethyl-l-methyl)-pentyl -CH(CH₃)CH₂C(C₂H₅)CH₂CH₃

Question 81.  Write the IUPAC name: CH₂=CH—CH=CH — C = CH
Answer:  Hexa-l,3-dien-5-yne

Question 82.  Write the structure and name of an alkane having five C- atoms which on bromination gives only one monobromo derivative.
Answer:  Neopentane [(CH₃)₄C];

Question 83. Write structures of two compounds which are metamers as well as position isomers.
Answer: CH₃CO(CH₂)₂CH₃, C₂H₅COC₂H₅

Question 84. Give an example of a carbonyl compound in which tautomerism does not take place.
Answer: Benzaldehyde (C₆H₅CHO)

Question 85.  Give an example of a 3° free radical containing six hyperconjugable hydrogens.
Answer: (CH₃CH₂)₃C

Question 86.Which is the most stable carbocation having the formula,
Answer: Terf-butyl cation, Me₃C

Question 87. Which has greater resonance stabilization—PhNH₂ or PhNH₃?
Answer: PhNH₂

Question 88. Write the name of a cyclic compound that is isomeric with but-l-ene.
Answer: Cyclobutane

Question 89.  Write the names of two non-polar solvents that are commonly employed for crystallization.
Answer: Benzene and carbon tetrachloride

Question 90.  What type of furnace is used in the Carius method for the estimation of halogens?
Answer: Bomb furnace

Question 91. Mention the type of chromatography in which both the mobile and stationary phases are liquid.
Answer: Paper chromatography

Question 92. With the help of which type of distillation process glycerol can be purified?
Answer: Distillation under reduced pressure

NCERT Solutions For Class 11 Chemistry Chapter 12 Organic Chemistry Basic Principles And Techniques

Fill In The Blanks

Question 1. When four alkyl groups are attached to a carbon atom, that particular C-atom is called _______________
Answer: 4°

Question 2. The shape of the molecule containing only sp² -hybridized carbon atoms is _______________
Answer: Planar

Question 3. The C-2 atom ofpropa-1,2-dieneis ________hybridised.
Answer: sp

Question 4. The shape of the molecule containing only sp-hybridized carbon atoms is_______________
Answer: Linear

Question 5. The successive members of a homologous series differ by _______________ mass units.
Answer: 14

Question 6. The molecule, HC = C—CH —CH — CH₃ contains _______________ a -bonds.
Answer: 10

Question 7. The molecule contains_______________ 2°H -atoms.
Answer: 4

Question 8. The general formula of dihydric alcohol is _______________
Answer: C_nH_2n(OH)₂

Question 9. The compound, 5-(l,2-dimethylpropyl)-6-ethyldecane contains _______________ 3° carbon atoms.
Answer: 4

Question 10. Stereoisomers have _______________ atom-to-atom bonding sequence or connectivity.
Answer: Same

Question 11. The number of isomers of a benzenoid aromatic compound having molecular formula, C₇H₈O is _______________
Answer: 5

Question 12. Ethoxyethane and 2-methoxy propane are related as _______________
Answer: 12 metamers

Question 13. The amount of negative charge present on each O-atom of carbonate ion is _______________
Answer: =-2/3

Question 14. The homolytic fission of a covalent bond requires _______________ energy than that required by its heterolytic c fission.
Answer: Less

Question 15. _______________ involves delocalization of σ -electrons of C — H bond of an alkyl group directly attached to an unsaturated system or to an atom with a vacant or singly p-orbital.
Answer: Hyperconjugation

Question 16. In paper chromatography, both the stationary and mobile phases are _______________
Answer: Liquid

Question 17. An impure sample of benzoic acid containing a little sodium chloride can be purified by _______________
Answer: Sublimation

Question 18. In steam distillation, the organic liquid boils at a _______________ temperature than its normal boiling point.
Answer: Lower

Question 19. In Cariu’s method of estimation, chlorine present in an organic compound is converted into _______________.
Answer: AgCl

Question 20. _______________ distillation is used to remove water from rectified spirit.
Answer: Azeotropic