JEE Chemistry Organic Chemistry Some Basic Principles and Techniques MCQs Set B

Question: Which of the following organic compound was synthesised by F. Wohler from an inorganic compound?

• a) Urea
• b) Chloroform
• c) Methane
• d) Acetic acid

Answer: Urea

Question: Geometry of methyl free-radical is

• a) planar
• b) linear
• c) pyramidal
• d) tetrahedral

Answer: planar

Question: In which of the following homolytic bond fission takes place ?

• a) Photochlorination of methane
• b) Nitration of benzene
• c) Addition of HBr to double bond
• d) Alkaline hydrolysis of ethyl chloride

Answer: Photochlorination of methane

Question: On exciting, Cl₂ molecules by UV light, we get

• a) 

  

• b) Cl^–
• c) Cl⁺
• d) all of these

Answer:

Question: The increasing order of stability of the following free radicals is

• a)

  

• b)

  

• c) Both
• d) None of these

Answer:

Question: Which of the following orders regarding relative stability of free radicals is correct?

• a) 3° > 2° < 1°
• b) 3° > 2° > 1°
• c) 3° < 2° < 1°
• d) 1° < 2° > 3°

Answer: 3° > 2° < 1°

Question: The most stable free radical among the following is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: For the reaction of phenol with CHCl₃ in presence of KOH, the electrophile is

• a) : CCl₂
• b) CCl₄
• c) 

  

• d)

  

Answer: : CCl₂

Question: The least stable free radical is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  Which of the following is strongest nucleophile

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Which of the following represents a set of nucleophiles?

• a)

  

• b)

  

• c)

  

• d) All of these

Answer:

Question: Which of the following species does not acts as a nucleophile?

• a) BF₃
• b) ROR
• c) ROH
• d) PCl₃

Answer: BF₃

Question: Which of the following is an electrophile ?

• a) Lewis acid
• b) Lewis base
• c) Negatively charged species
• d) None of the above

Answer: Lewis acid

Question:  Which of the following pairs represent electrophiles?

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a) B and D
• b) C and D
• c) B, C and D
• d) C only

Answer: B and D

Question:  Arrangement of (CH₃)₃ – C –, (CH₃)₂ – CH –, CH₃ – CH₂ – when attached to benzyl or an unsaturated group in increasing order of inductive effect is

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Polarization of electrons in acrolein may be written as

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Point out the incorrect statement about resonance?

• a) In resonating structures, there should not be same number of electron pairs
• b) Resonating structures should differ only in the location of electrons around the constituent atoms
• c) In resonating structures, the constituent atoms must be in the same position
• d) Resonance structures should have equal energy

Answer: In resonating structures, there should not be same number of electron pairs

Question:

• a) resonating structures
• b) geometrical isomers
• c) tautomers
• d) optical isomers

Answer: resonating structures

Question:  In which of the following, resonance will be possible?

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

More Questions..........................

Question: Which of the following statements regarding the resonance energy of benzene is correct?

• a) Resonance energy is the energy required to convert
• b) Resonance energy is the energy required to convert
• c) Resonance energy is the energy required to break the C–C bond in benzene
• d) Resonance energy is the energy required to break the C–H bond in benzene

Answer: Resonance energy is the energy required to convert

Question: Which of the following is not correctly matched ?

• a)

  

                   

• b)

  

                

• c) Both
• d) None of these

Answer:

Question:

• a) Resonance effect
• b) Inductive effect
• c) Electromeric effect
• d) Hyperconjugation

Answer: Resonance effect

Question: Electromeric effect is a

• a) temporary effect
• b) inductive effect
• c) permanent effect
• d) resonance effect

Answer: temporary effect

Question: The kind of delocalization involving sigma bond orbitals is called

• a) hyperconjugation effect
• b) mesomeric effect
• c) inductive effect
• d) electromeric effect

Answer: hyperconjugation effect

Question: Hyperconjugation involves overlap of the following orbitals

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Choose the correct order of stability of carbocation using concept of hyperconjugation.

• a) IV < III < II < I
• b) None of these
• c) I < II < III < IV
• d) III < IV < II < I

Answer: IV < III < II < I

Question: Hyperconjugation is most useful for stabilizing which of the following carbocations ?

• a) tert-Butyl
• b) Ethyl
• c) neo-Pentyl
• d) iso-Propyl

Answer: tert-Butyl

Question: Which of the following is an example of elimination reaction?

• a) Dehydration of ethanol
• b) Nitration of benzene
• c) Hydroxylation of ethylene
• d) Chlorination of methane

Answer: Dehydration of ethanol

Question:

• a) substitution
• b) elimination
• c) addition
• d) rearrangement

Answer: substitution

Question: Which of the following method is not used for determining purity of a compound ?

• a) All of the above parameters are used for determining the purity of a compound.
• b) Chromatographic techniques
• c) Melting point
• d) None of these

Answer: All of the above parameters are used for determining the purity of a compound.

Question: Which of the following is not the criteria of purity of a substance?

• a) solubility
• b) boiling point
• c) melting point
• d) density

Answer:  solubility

Question: In crystallisation process impurities which impart colour to the solution are removed by which of the following ?

• a) Activated charcoal
• b) Repeated crystallisation
• c) Bleaching agent
• d) None of these

Answer: Activated charcoal

Question: Aniline is purified by

• a) steam distillation
• b) vacuum distillation
• c) simple distillation
• d) extraction with a solvent

Answer: steam distillation

Question: Which is purified by steam distillation

• a) Aniline
• b) Petroleum
• c) Benzoic acid
• d) Naphthalene

Answer: Aniline

Question:  The best method for the separation of naphthalene and benzoic acid from their mixture is

• a) sublimation
• b) crystallisation
• c) distillation
• d) chromatography

Answer: sublimation

Question: In steam distillation the vapour pressure of volatile organic compound is

• a) more than atmospheric pressure
• b) less than atmospheric pressure
• c) double the atmospheric pressure
• d) equal to atmospheric pressure

Answer: more than atmospheric pressure

Question: Fractional distillation is used when

• a) there is a small difference in the boiling points of liquids
• b) there is a large difference in the boiling point of liquids
• c) boiling points of liquids are same
• d) liquids form a constant boiling mixture

Answer: there is a small difference in the boiling points of liquids

Question: Purification of petroleum is carried out by

• a) fractional distillation
• b) vacuum distillation
• c) steam distillation
• d) simple distillation

Answer: fractional distillation

Question: A liquid decomposes at its boiling point. It can be purified by

• a) vacuum distillation
• b) steam distillation
• c) fractional distillation
• d) sublimation

Answer: vacuum distillation

Question: Distillation under reduced pressure is employed for

• a) CH₂OHCHOHCH₂OH
• b) petrol
• c) C₆H₆
• d) None of these

Answer: CH₂OHCHOHCH₂OH

Question: Impure glycerine is purified by

• a) vacuum distillation
• b) steam distillation
• c) simple distillation
• d) None of these

Answer: vacuum distillation

Question: The latest technique for the purification of organic compounds is

• a) Silica gel
• b) Zeolite
• c) Alumina
• d) None of these

Answer:  Silica gel

Question: Which of the following acts as the stationary phase in paper chromatography

• a) Both
• b) Alumina
• c) Silica gel
• d) None of these

Answer: Both

Question: Which of the following acts as the stationary phase in paper chromatography ?

• a) Water
• b) Silica gel
• c) Alumina
• d) None of these

Answer: Water

Question:  The most satisfactory method to separate mixture of sugars is

• a) chromatography
• b) fractional crystallisation
• c) sublimation
• d) benedict reagent

Answer: chromatography

Question: Glycerol can be separated from spent lye in soap industry by which of the following method

• a) Distillation under reduced pressure
• b) Fractional distillation
• c) Steam distillation
• d) Differential extraction

Answer: Distillation under reduced pressure

Question: Chromatography is a valuable method for the separation, isolation, purification and identification of the constituents of a mixture and it is based on general principle of

• a) phase distribution
• b) phase operation
• c) phase rule
• d) interphase separation

Answer:  phase distribution

Question: In paper chromatography

• a) moving phase is liquid and stationary phase is liquid
• b) moving phase is solid and stationary phase is solid
• c) moving phase is solid and stationary phase is liquid
• d) moving phase is liquid and stationary phase in solid

Answer: moving phase is liquid and stationary phase is liquid

Question: Which of the following is used for detection of carbon and hydrogen ?

• a) CuO
• b) KOH
• c) CaCl₂
• d) None of these

Answer: CuO

Question:  In sodium fusion test of organic compounds, the nitrogen of the organic compound is converted into

• a) sodium cyanide
• b) sodium nitrate
• c) sodamide
• d) sodium nitrite

Answer: sodium cyanide

Question: Which of the following compounds does not show Lassaigne’s test for nitrogen ?

• a) Hydrazine
• b) Azobenzene
• c) Urea
• d) Phenylhydrazine

Answer: Hydrazine

Question: The compound formed in the positive test for nitrogen with the Lassaigne solution of an organic compound is

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: In quantitative analysis of carbon and hydrogen, the mass of water produced is determined by passing the mixture through a weighed U – tube containing ___X___ and carbon dioxide is absorbed in concentrated solution of ___Y___

• a) X = CaCl₂ , Y = KOH
• b) X = CaCl₂ , Y = NaOH
• c) Both
• d) None of these

Answer: X = CaCl₂ , Y = KOH

Question: Kjeldahl method is not applicable to which of the following ?

• a) All of these
• b) Azo compounds
• c) Nitro compounds
• d) Pyridine

Answer: All of these

Question: Nitrogen in an organic compound can be estimated by

• a) Both
• b) Kjeldahl’s method only
• c) Duma’s method only
• d) None of these

Answer: Both

Question: Duma's method involves the determination of nitrogen content in the organic compound in form of

• a) N₂
• b) NH₃
• c) NaCN
• d) None of these

Answer: N₂

Question: In Kjeldahl’s method nitrogen present is estimated as

• a) NH₃
• b) None of these
• c) N₂
• d) NO₂

Answer: NH₃

Question: In kjeldahl's method of estimation of nitrogen, K₂SO₄ acts as

• a) boiling point elevator
• b) catalytic agent
• c) oxidising agent
• d) hydrolysing agent

Answer: boiling point elevator

Question: 0.5g of an organic compound containing nitrogen on Kjeldahlising required 29 mL of N/5 H2SO4 for complete neutralization of ammonia. The percentage of nitrogen in the compound is

• a) 16.2
• b) 14.8
• c) 34.3
• d) 21.6

Answer: 16.2

Question: The percentage of sulphur in an organic compound whose 0.32 g produces 0.233 g of BaSO4 [At. wt. Ba = 137, S = 32] is

• a) 10.0
• b) 32.1
• c) 1.0
• d) 23.5

Answer: 10.0

Question: An organic compound contains C = 40%, H = 13.33% and N = 46.67%. Its empirical formula would be

• a) CH₄N
• b) CHN
• c) C₂H₂N
• d) None of these

Answer:  CH₄N

Question: 2.79 g of an organic compound when heated in Carius tube with conc. HNO₃ and H₃PO₄ formed converted into MgNH₄.PO₄ ppt. The ppt. on heating gave 1.332 g of Mg₂P₂O₇ . The percentage of P in the compound is

• a) 13.33%
• b) 26.66%
• c) 23.33%
• d) 33.33%

Answer: 13.33%

Question: A compound contains 38.8% C, 16% H and 45.2% N. The formula of compound would be

• a) CH₃NH₂
• b) C₂H₅CN
• c) CH₃CN
• d) None of these

Answer: CH₃NH₂

Question:  In estimation of percentage of oxygen. The mixture of gaseous products containing oxygen is passed over red hot coke. All oxygen is converted to A . This mixture is passed through B when A is converted to _ C .

What is A, B and C in above statement.

• a) A = CO , B = I₂O₅ , C = CO₂
• b) A = CO , B = I₂ , C = CO₂
• c) A = CO₂ , B = KOH , C = pure O₂
• d) None o these

Answer: A = CO , B = I₂O₅ , C = CO₂

Question:

• a) (ii) only
• b) (i) and (iii)
• c) (ii) and (iii)
• d) (i) only

Answer:  (ii) only

Question:

• a) TTF
• b) FFF
• c) FFT
• d) TTT

Answer: TTF

Question:

• a) (i) and (iii)
• b) (i) only
• c) (ii) only
• d) (i), (ii) and (iii)

Answer:  (i) and (iii)

Question: Which of the following sequence of T and F is correct for given statements. Here T stands for correct and F stands for false statement

(i) The more the number of contributing structures, the more is the resonance energy.
(ii) The resonance structures have different positions of nuclei but same number of unpaired electrons
(iii) The energy of actual structure of the molecule (the resonance hybrid) is lower than that of any of the canonical structures.

• a) TFT
• b) TFF
• c) TTT
• d) FFF

Answer: TFT

Question:  Which of the following statements are correct for fractional distillation ?

(i) Fractional distillation method is used if the two liquids have sufficiently large difference in their boiling points.
(ii) A fractionating column provides many surfaces for heat exchange between the ascending vapours and the descending condensed liquid.
(iii) Each successive condensation and vaporisation unit in the fractionating column is called a theoretical plate.
(iv) Fractional distillation method is used to separate different fractions of crude oil in petroleum industry.

• a) (ii), (iii) and (iv)
• b) (i), (ii), (iii) and (iv)
• c) (i), (ii) and (iv)
• d) (i), (ii) and (iii)

Answer: (ii), (iii) and (iv)

Question:

• a) TFTF
• b) TFFF
• c) TTTF
• d) TTTT

Answer: TFTF