12th class (Fsc) Chemistry unit 10 MCQs
76. Alkyl halide are considered to be very reactive compounds towards nucleophiles, because:
a. They have an electrophilic carbon and a bad leaving group
b. They have an electrophilic carbon
c. They have a nucleophilic carbon and a good leaving group
d. They have an electrophilic carbon and a good leaving group
77. The rate of E1 reaction depends upon:
a. The poncentration os substance as well as nucleophile
b. The concentration of substance
c. None of the above
d. The concentration of nucleophile
78. Which one of the following is not a nucleophile:
a. BF3
b. H2
c. NH3
d. H2S
79. The common name to 2-methyl-chloropropane is:
a. Ter.butyl chloride
b. Iso-butyl bromide
c. N-butyl chloride
d. Sec. buyl halide
80. IN primary alkyl halides, the halogen atom is attached to a carbon atom which is furthur attached to how many carbon atoms
a. One
b. Two
c. Four
d. Three
81. Which one of the following is not a necleophile:
a. BF3
b. H2O
c. NH3
d. H2S
82. Which one of the following is lectrophile:
a. BF3
b. NH3
c. CI2
d. H2O
83. H3O+ has one lone pair of electrons on oxygen. It can act as:
a. Strong acid
b. Lewis acid
c. Ether
d. Nucleophile
84. In SN2 mechanism, the hybridization of carbon atoms changes from sp3 to:
a. Dsp3
b. Sp
c. Dsp2
d. Sp2
85. In SN 2 mechanism, the hybridization of carbon atom changes from sp3 to:
a. Dsp3
b. Sp2
c. Sp
d. None of these
86. SN2 mechanism involves:
a. 3rd order kinetics
b. 1st order kinetics
c. Zero order kinetics
d. 2nd order kinetics
87. The order of typical SN2 reaction is:
a. 3rd
b. 1st
c. Zero
d. 2nd
88. For which mechanism the first step involved in the same:
a. SN 1 and E2
b. E1 and E2
c. E1 and SN 1
d. E2 and SN2
89. The order of a typical SN 2 reaction is:
a. Second
b. Zero
c. Third
d. First
90. SN 1 reactions are easily given by:
a. Secondary alcohols
b. Primary alkyl halides
c. Primary alcohols
d. Secondary alkyl halides
91. Reaction of CO2 with ethyl ,magnesium bromide, followed by acid hydrolysis product:
a. Proponal
b. Propane
c. Propanol
d. Propanoic acid
92. When purely alcoholic solution of sodium / potassium hydroxide and halogenoalkanes are reacted an alkene is formed, what is the mechanism of reaction?
a. Denomination
b. Elimination
c. Reduction of benzene
d. Dehydration
93. The organic compound carbon tetrachloride is used as:
a. Oxidant
b. Lubricant
c. Plastic
d. Solvent
94. The alkaline hydrolysis od bromoethane shown below gives alcohol as the product: H3C-CH2-Br → H3C – CH2 – OH the reagent and the condition used in this reactions may be:
a. KOH in alcohol
b. H2O at room temperature
c. Dilute NaOH(aq) warm
d. Ethanol, heat
95. In substitution reactions, dihaloalkane or secondary halogenoalkane give/ show:
a. SN 1 mechanism
b. S2N mechanism
c. Both E1 and E2
d. Both SN1 and SN2
96. The order of reactivity of alkyl halides towards nucleophile is:
a. RI>RBr>RCI>RF
b. RI>RBr>RF>RCI
c. RF>RBr>RCI>RI
d. RF>RCI>RBr>RI
97. The halothane used in hospitals as an anesthetic is chemically.
a. 1,1,1-triflouro-2- bromo-2- chloroethane
b. 1-bromo-1- chloro-2,2,2- trifluroethane
c. 2-chloro-2- bromo-1,1,1- triflouromoethane
d. 2-bromo-2- chloro-1,1,1- trifluroethene
98. If halogenoalkanes are mixed with an access of ethanoic ammonia and heated under pressure, amine are formed, which amine is formed in the following reaction? CH2CH2Br+NH3 → Amine.
a. CH3 -CH2 -N2
b. CH3 -CH2 -NH- CH2 – CH3
c. H2 N-CH2 -CH2 – NH2
d. CH3 -CH2 -CH2 – NH2
99. Consider the reaction given below: CH3CH2Br → H2 C=CH2 +HBr mechanism followed by the raction is:
a. E1
b. E2
c. SN2
d. SN1
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