Chemistry Chapter 15 Entry Test MCQs
51. CH3Br + Nu–→ CH3 – Nu– + Br– . The decreasing order of the rate of above reaction with nucleophile 1 to 4 is Nu– = (1) F– (2) OH– (3) NH2– (4) I–
a. 1 > 2 > 3 > 4
b. 4 > 3 > 1 > 2
c. 4 > 3 > 2 > 1
d. 2 > 4 > 3 > 1
52. Consider the following haloalkanes:
- CH3F 2. CH3Cl 3. CH3Br 4. CH3I The increasing order of reactivity in nucleophilic substitution reaction is
a. 4 < 3 < 2 < 1
b. 1 < 3 < 2 < 4
c. 1 < 2 < 3 < 4
d. 1 < 2 < 4 < 3
53. What will be the main product when ammonia reacts with limited amount of ethylbromide?
a. (C2H5)4N+
b. (C2H5)2NH
c. C2H5NH2
d. (C2H5)3N
54. When bromoethane is refluxed with a purely alcoholic solution of sodium hydroxide, then the product obtained is:
a. Sodium acetate
b. Ethanol
c. Ethene
d. Sodium ethoxide
55. During SN1 mechanism of nucleophillic substitution reactions, when concentration of attacking nucleophile is tripled then the rate of reaction:
a. Decreases to one third
b. Increases 3 – times
c. do not increase
d. Increase 9 – times
56. In the nucleophilc substitution reaction of alkyl halide, the electrophilic character are more prominent in:
a. C3H7 – Br
b. CH3Br
c. C2H5 – Br
d. All have same
57. For a given halogen the order of reactivity for SN2 mechanism is as follows?
a. C3H7X < C2H5X < CH3X
b. CH3X < C2H5X < C3H7X
c. C2H5X < C3H7X < CH3X
d. C3H7X < CH3X < C2H5X
58. Which one of the following reagents does not change ethyl alcohol to ethyl chloride?
a. PCl3
b. HCl + ZnCl2
c. Aqueous KOH
d. SOCl2 in pyridine
59. Elimination unimolecular involves:
a. 3rd order kinetics
b. 1st order kinetics
c. Zero order kinetics
d. 2nd order kinetics
60. During ring SN2 mechanism, carbon atom changes its state of hybridization from_______
a. sp3→sp
b. sp→sp2
c. sp3→sp2
d. sp2→sp3
61. During ring SN2 mechanism, ultimate change in the state of hybridization of carbon is from___
a. sp3→sp2
b. sp→sp2
c. sp3→sp
d. sp2→sp3
62. The relative nucleophilicity of H3N, H2O and HF towards bromoethane is
a. H3N > H2O < HF
b. H3N < H2O < HF
c. H3N < H2O > HF
d. H3N > H2O > HF
63. The hydrolysis of 2-bromo-3-methylbutane yields.
a. 3-methylbutanol
b. 3- methyl-2-butanol
c. 2-methylbutanol
d. 2- methyl-2-butanol