AIEEE Chemistry Practice Paper 8

STABILITY OF RESONATING STRUCTURES Q.1 The second most favourable structure of vinyl chloride is-(A) ?? CH2 – CH = Cl . . : ? (B) CH2 = CH – Cl . . . . : (C) CH ? 2 – CH = ?? : . . Cl (D) All equal Q.2 Stability of CH ? 2 – CH = CH2 can be explained by : (A) Inductive effect (B) Electromeric effect (C) Resonance (D) Polar effect Q.3 The correct decreasing order of stability of following resonance structures of vinyl chloride is CH2 = CH — Cl ? ? ? CH CH Cl ? 2 — ? ? ? ? ? CH CH Cl ? ? 2 — ? (I) (II) (III) (A) I > II > III (B) II > I > III (C) I > II = III (D) III > II > I Q.4 Which of the following resonance structures is the major contributor to the resonance hybrid? (A) I (B) II (C) Both have equal contribution (D) They are not resonance structures Q.5 Acyl cation has two resonating structures which are given below : ? ???????????????????????? R – C = O R – C ? O (I) (II) Which statement is correct for (I) and (II) (A) (I) is more stable than two (B) (II) is more stable than one (C) Stability of (I) and (II) will be same (D) For some time (I) will be more stable and for remaining time (II) will be more stable.Q.6 Which of the following is the most stable resonance structure ? (A) H C 3 CH2 ? (B) H C 3 CH2 ? (C) H C 3 CH2 ? (D) H C 3 CH2 ? Q.7 The relative importance of the following resonance contributors : i ii iii (A) i > ii > iii (B) ii > iii > i (C) i > iii > ii (D) iii > ii > i Q.8 Arrange the following resonating structures in the order of decreasing stability. H C O H O ? ? ? || ? :??: | O H C O H ? ? ? ? ? ? : ??: | . . . . O H C O ? ? ? ? –H ? : : |.. . . . . O H C OH ? ? ? (I) (II) (III) (IV) (A) I > II > III > IV (B) I > III > II > IV (C) II > III > IV > I (D) II > IV > III > I Q.9 Arrange the following in decreasing order of stability I II III (A) I = II > III (B) I > II > III (C) III > I = II (D) III > I > IIQ.10 The most stable resonance form is I II (A) I (B) II (C) Both have equal contribution (D) They are not resonance structures ANSWER KEY Q.No. 1 2 3 4 5 6 7 8 9 10 Ans. A C A B B A C A A B