Free NEET Chemistry multiple-choice questions on Electronic Displacements. Attempt each question and reveal the answer with a full explanation.
Which of the following species acts as an electrophile? BF 3 NH 3 H 2O OH - Stability of the following free radicals is in the order: (CH 3) 3 C > (CH 3) 2 C H > CH 3 C H 2 > C H 3 C H 3 > CH 3 C H 2 > (CH 3) 2 C H > (CH 3) 3 C (CH 3) 3 C > CH 3 C H 2 > (CH 3) 2 C H > C H 3 (CH 3) 2 C H > (CH 3) 3 C > CH 3 C H 2 > C H 3 The displacement of electrons in a multiple bond in the presence of an attacking reagent is called: Electromeric effect Inductive effect Resonance effect Hyperconjugation Which of the following effects is responsible for the stability of tertiary butyl carbocation? Hyperconjugation Resonance effect Electromeric effect Mesomeric effect Which of the following is the most stable free radical? Triphenylmethyl radical Benzyl radical Allyl radical Tert-butyl radical Which electronic effect is responsible for the 'Baker-Nathan Effect'? Hyperconjugation Inductive effect Electromeric effect Mesomeric effect Which among the given compounds is the most acidic? Trichloroacetic acid Dichloroacetic acid Monochloroacetic acid Acetic acid Which electronic effect involves the complete transfer of a shared pair of π -electrons to one of the atoms in the presence of an attacking reagent? Electromeric effect Inductive effect Resonance effect Hyperconjugation Which of the following does not show resonance? CH 3-CH 2-CH 2-OH CH 2=CH-CH=CH 2 C 6H 5-OH CH 2=CH-Cl The inductive effect of which group is taken as zero for comparison? -H -CH 3 -Cl -NO 2 The correct order of increasing -I effect of the following groups is: -I < -Br < -Cl < -F -F < -Cl < -Br < -I -Cl < -F < -Br < -I -Br < -I < -Cl < -F Which of the following acts as the electrophile in the nitration of benzene? NO 2 + NO 2 NO 2 - HNO 3 Which effect involves the delocalization of σ -electrons of C-H bond of an alkyl group directly attached to an atom of unsaturated system? Hyperconjugation Inductive effect Electromeric effect Resonance effect Which of the following is the most acidic compound? 2,4,6-Trinitrophenol Phenol p-Nitrophenol o-Cresol The phenomenon of resonance is not observed in: Cyclohexane Benzene Vinyl chloride Nitrobenzene Which of the following effects is permanent and involves the displacement of -electrons? Inductive effect Electromeric effect Mesomeric effect Hyperconjugation Which of the following is a neutral electrophile? SO 3 H 3O + NO 2 + CH 3 + Resonance energy is defined as the difference in energy between: The most stable resonating structure and the resonance hybrid. The least stable resonating structure and the resonance hybrid. Two different resonating structures. The ground state and the excited state of a molecule. Which of the following represents the correct order of the acidity in the given compounds? FCH2COOH > CH3COOH > BrCH2COOH > ClCH2COOH BrCH2COOH > ClCH2COOH > FCH2COOH > CH3COOH FCH2COOH > ClCH2COOH > BrCH2COOH > CH3COOH CH3COOH > BrCH2COOH > ClCH2COOH > FCH2COOH Which of the following shows the maximum number of hyperconjugation structures? 2-Butene Propene Ethene 1-Butene Which of the following is the correct order of -I effect? -NO 2 > -CN > -F > -OH -OH > -F > -CN > -NO 2 -NH 2 > -OH > -F > -NO 2 -CN > -NO 2 > -OH > -F Which of the following can show both +M and -I effects? -Cl -CH 3 -NO 2 -CN The presence of an -OH group on the benzene ring activates the ring towards electrophilic substitution because of: +M effect -I effect -M effect +I effect Which of the following is the correct order of decreasing stability for the given carbocations? (I) C 6H 5CH 2 + , (II) CH 2=CH-CH 2 + , (III) CH 3-CH 2-CH 2 + I > II > III II > I > III III > II > I I > III > II In which of the following, the resonance effect is NOT possible? CH 2=CH-CH 2-Cl CH 2=CH-Cl C 6H 5-Cl CH 2=CH-CH=CH 2 Which of the following compounds will give a positive Lassaigne's test for both Nitrogen and Sulfur? NH 2CONHNH 2 HCl Thiocarbamide Aniline Sodium acetate The correct order of basic strength of methyl substituted amines in aqueous solution is: (CH 3) 2NH > CH 3NH 2 > (CH 3) 3N > NH 3 (CH 3) 3N > (CH 3) 2NH > CH 3NH 2 > NH 3 (CH 3) 3N > CH 3NH 2 > (CH 3) 2NH > NH 3 (CH 3) 2NH > (CH 3) 3N > CH 3NH 2 > NH 3 In the Carius method of estimation of halogen, 0.15 g of an organic compound gave 0.12 g of AgBr . The percentage of bromine in the compound is: (Atomic mass: Ag = 108, Br = 80 ) 34.04% 40.12% 25.33% 48.55% Which of the following is the most stable alkene according to the concept of hyperconjugation? 2,3-Dimethylbut-2-ene But-2-ene Propene Ethene Which of the following oxygen-containing groups shows the strongest -I effect? -O + R 2 -OH -OR -O - The number of hyperconjugative structures possible for the radical CH 3-ṄH-CH 2-CH 3 is: 5 6 3 2 Which of the following is most reactive towards electrophilic substitution? Aniline Benzene Nitrobenzene Chlorobenzene In which of the following compounds, the inductive effect is minimum? CH 3-CH 2-CH 2-Cl CH 3-CH 2-Cl CH 3-Cl CH 3-CH 2-CH 2-CH 2-Cl Which of the following is a 'nucleophilic' reagent? NH 3 BF 3 AlCl 3 NO 2 + During the estimation of halogens by the Carius method, 0.20 g of an organic compound gave 0.188 g of silver bromide ( AgBr ). The percentage of bromine in the compound is: (Atomic mass: Ag=108, Br=80 ) 40% 32% 46% 20% Kjeldahl's method for the estimation of nitrogen is NOT applicable to which of the following compounds? Nitrobenzene Aniline Urea Acetamide Which of the following carbocations is the most stable due to resonance and inductive effects? (C 6H 5) 3C + (CH 3) 3C + C 6H 5CH 2 + CH 2=CH-CH 2 + Which of the following reagents is an electrophile? SO 3 NH 3 H 2O OH - Which of the following compounds is the most acidic? O 2N-CH 2-COOH Cl-CH 2-COOH CH 3-COOH CH 3-CH 2-COOH The correct order of nucleophilicity in a polar protic solvent is: I - > Br - > Cl - > F - F - > Cl - > Br - > I - Cl - > F - > Br - > I - I - > F - > Br - > Cl - Which of the following is the correct order of stability for the following carbanions? (I) F-CH 2 - , (II) Cl-CH 2 - , (III) Br-CH 2 - I > II > III III > II > I II > I > III I = II = III Which of the following aromatic rings is most reactive towards electrophilic substitution? Aniline Benzene Nitrobenzene Chlorobenzene Which of the following carbocations is the most stable due to back-bonding/resonance? CH 3-O-CH 2 + CH 3-CH 2-CH 2 + CH 2=CH-CH 2 + (CH 3) 2CH + The resonance stabilization of the phenoxide ion is more effective than that of phenol because: In phenoxide, there is no charge separation. In phenol, the oxygen is more electronegative. Phenoxide has more resonating structures. Phenoxide is more symmetrical. Which of the following is most acidic? HC≡CH CH 2=CH 2 CH 3-CH 3 CH 3-CH=CH 2 Hyperconjugation is most effective in which of the following molecules? Toluene Ethylbenzene Isopropylbenzene tert-Butylbenzene In which direction does the Electromeric (+E) effect work in the reaction of H + with propene? Towards the terminal carbon CH 2 Towards the central carbon CH Towards the methyl group CH 3 Equally in both directions The total number of and bonds in toluene ( C 6H 5CH 3 ) is: 15 and 3 12 and 3 15 and 6 14 and 3 Which of the following represents the correct order of the -I effect of the given groups? -F > -OH > -NH 2 -NH 2 > -OH > -F -F > -NH 2 > -OH -OH > -F > -NH 2 Which of the following groups shows both a +M (mesomeric) effect and a -I (inductive) effect? -Cl -CH 3 -NO 2 -COOH In which of the following molecules is the inductive effect of the methyl group +I ? CH 3-Li CH 3-F CH 3-OH CH 3-Cl Kjeldahl's method cannot be used to estimate nitrogen in which of the following compounds? Nitrobenzene Urea Acetamide Ethylamine Which of the following is the most stable resonance structure of Nitrobenzene? The structure with the benzene ring remaining fully benzenoid. The structure with a positive charge on the ortho carbon. The structure with a positive charge on the para carbon. The structure with a negative charge on the ring. Which of the following has the highest nucleophilicity in water (polar protic solvent)? I - Br - Cl - F - The bond between C2 and C3 in CH 2=CH-CH=CH 2 is shorter than a normal C-C single bond because of: Resonance Inductive effect Electromeric effect Hyperconjugation Which of the following is a null-inductive ( I=0 ) reference group? -H -CH 3 -D -T Consider the following compounds. (i) C6H5COCl (ii) p - O2N-C6H4-COCl (iii) p - H3C-C6H4-COCl (iv) p - OHC-C6H4-COCl The correct decreasing order of their reactivity towards hydrolysis is (i) > (ii) > (iii) > (iv) (iv) > (ii) > (i) > (iii) (ii) > (iv) > (i) > (iii) (ii) > (iv) > (iii) > (i) Match Column-I with Column-II: A–R; B–Q; C–P A–P; B–Q; C–R A–Q; B–R; C–P A–R; B–P; C–Q Which of the following carbocations is expected to be most stable? Which of the following is correct with respect to -I effect of the substituents? (R = alkyl) -NH2 > -OR > -F -NR2 < -OR < -F -NH2 < -OR < -F -NR2 > -OR > -F Match List I with List II. Choose the correct answer from the options given below: A-IV, B-I, C-III, D-II A-III, B-I, C-II, D-IV A-IV, B-I, C-II, D-III A-I, B-IV, C-II, D-III Which of the following is an example of a +E (Electromeric) effect? Addition of H + to an alkene Addition of CN - to a carbonyl group Resonance in benzene Inductive effect in alkyl halides Which of the following shows the correct order of decreasing +I effect? -O - > -COO - > -(CH 3) 3C > -CH 3 -CH 3 > -(CH 3) 3C > -COO - > -O - -COO - > -O - > -CH 3 > -(CH 3) 3C -(CH 3) 3C > -CH 3 > -O - > -COO - The reaction that involves the Steric Inhibition of Resonance (SIR effect) is most prominent in: 2,6-Dimethylbenzoic acid Benzoic acid p-Tolulic acid o-Nitrophenol Arrange the following in increasing order of +M effect: -OH, -NH 2, -NHR, -OCH 3 . -OCH 3 < -OH < -NHR < -NH 2 -OH < -OCH 3 < -NH 2 < -NHR -OCH 3 < -OH < -NH 2 < -NHR -NH 2 < -NHR < -OH < -OCH 3 In the Carius method, 0.1 g of an organic compound gave 0.094 g of AgBr . The percentage of bromine in the compound is: (Atomic mass: Ag=108, Br=80 ) 40% 20% 60% 80% The correct order of increasing acidic strength for: (I) CH 3COOH , (II) CH 2ClCOOH , (III) CHCl 2COOH is: I < II < III III < II < I II < I < III I < III < II Arrange the following in increasing order of acidic strength: (I) Benzoic acid, (II) o -Nitrobenzoic acid, (III) p -Nitrobenzoic acid. I < III < II I < II < III II < III < I III < I < II In a polar aprotic solvent like DMSO, the correct order of nucleophilicity of halide ions is: F - > Cl - > Br - > I - I - > Br - > Cl - > F - Cl - > F - > I - > Br - F - = Cl - = Br - = I - Among the following, the most stable carbocation is: (C 6H 5) 3C + (CH 3) 3C + (C 6H 5) 2CH + CH 2=CH-CH 2 + Which of the following is the correct order of basicity for methyl-substituted amines in the gaseous phase? (CH 3) 3N > (CH 3) 2NH > CH 3NH 2 > NH 3 (CH 3) 2NH > CH 3NH 2 > (CH 3) 3N > NH 3 (CH 3) 2NH > (CH 3) 3N > CH 3NH 2 > NH 3 NH 3 > CH 3NH 2 > (CH 3) 2NH > (CH 3) 3N The dipole moment of chlorobenzene is: Lower than that of methyl chloride Higher than that of methyl chloride Zero Same as that of methyl chloride The correct order of -I effect of the following species is: -NH 3 + > -NO 2 > -CN > -COOH -NO 2 > -NH 3 + > -CN > -COOH -COOH > -CN > -NO 2 > -NH 3 + -CN > -NO 2 > -COOH > -NH 3 + The following carbocation is stabilized by the interaction of the empty p orbital with filled and filled orbitals empty and empty orbitals empty and filled orbitals empty and empty orbitals Arrange the following carbocations in increasing order of stability: (I) CH 3 + , (II) CH 3CH 2 + , (III) (CH 3) 2CH + , (IV) (CH 3) 3C + . I < II < III < IV IV < III < II < I I < III < II < IV III < II < I < IV Which of the following represents the correct order of electron-withdrawing effect ( -I effect)? -F > -Cl > -Br > -I -I > -Br > -Cl > -F -Cl > -F > -Br > -I -F > -Br > -Cl > -I