131. Reaction of $${C_6}{H_5}C{H_2}Br$$ with aqueous sodium hydroxide follows _________.
A
$${S_N}1$$ mechanism
B
$${S_N}2$$ mechanism
C
Any of the above two depending upon the temperature of reaction
D
Saytzeff rule
Answer :
$${S_N}1$$ mechanism
132. Grignard reagent, a very useful starting compound for a number of organic reactions can be prepared by
A
reaction of alkyl halides with a solution of magnesium hydroxide
B
reaction of alkyl halides with dry magnesium powder in presence of dry ether
C
reaction of \[MgC{{l}_{2}}\] with ether and alcohol
D
reaction of alkyl halide with magnesium in presence of alcohol
Answer :
reaction of alkyl halides with dry magnesium powder in presence of dry ether
133.
Arrange the following compounds in the increasing order of their densities.
A
(I) < (II) < (III) < (IV)
B
(I) < (III) < (IV) < (II)
C
(IV) < (III) < (II) < (I)
D
(II) < (IV) < (III) < (I)
Answer :
(I) < (II) < (III) < (IV)
134. A major component of Borsch reagent is obtained by reacting hydrazine hydrate with which of the following ?
A
B
C
D
Answer :
135. The IUPAC name of tertiary butyl chloride is
A
2-chloro-2-methylpropane
B
3-chlorobutane
C
4-chlorobutane
D
1, 2-chloro-3-methylpropane
Answer :
2-chloro-2-methylpropane
136. An alkyl halide with molecular formula, $${C_6}{H_{13}}Br$$ on dehydrohalogenation gives two isomeric alkenes $$X$$ and $$Y$$ with molecular formula, $${C_6}{H_{12}}.$$ On reductive ozonolysis $$X$$ and $$Y$$ gave four compounds $$C{H_3}COC{H_3},C{H_3}CHO,$$ $$C{H_3}C{H_2}CHO$$ and $${\left( {C{H_3}} \right)_2}CHCHO.$$ The alkyl halide is
A
4-bromo-2-methylpentane
B
3-bromo-2-methylpentane
C
2-bromo-2, 3-dimethylbutane
D
2, 2-dimethyl-1-bromobutane
Answer :
3-bromo-2-methylpentane
137.
Which one of the following reagents is not suitable for the elimination reaction ?
A
$$NaI/{\text{acetone}}$$
B
$$NaOEt/EtOH$$
C
$$NaOH/{H_2}O$$
D
$$NaOH/{H_2}O = EtOH$$
Answer :
$$NaI/{\text{acetone}}$$
138. Which of the following is most reactive towards aqueous $$NaOH?$$
A
$${C_6}{H_5}Cl$$
B
$${C_6}{H_5}C{H_2}Cl$$
C
$${C_6}{H_5}Br$$
D
$$Br{C_6}{H_4}Br$$
Answer :
$${C_6}{H_5}C{H_2}Cl$$
139. Bottles containing $${C_6}{H_5}I$$ and $${C_6}{H_5}C{H_2}I$$ lost their original labels. They were labelled $$A$$ and $$B$$ for testing. $$A$$ and $$B$$ were separately taken in test tubes and boiled with $$NaOH$$ solution. The end solution in each tube was made acidic with dilute $$HN{O_3}$$ and then some $$AgN{O_3}$$ solution was added. Substance B gave a yellow precipitate. Which one of the following statements is true for this experiment ?
A
$$A$$ and $${C_6}{H_5}C{H_2}I$$
B
$$B$$ and $${C_6}{H_5}I$$
C
Addition of $$HN{O_3}$$ was unnecessary
D
$$A$$ was $${C_6}{H_5}I$$
Answer :
$$A$$ was $${C_6}{H_5}I$$
140. Aryl halides are less reactive towards nucleophilic substitution reactions as compared to alkyl halides due to
A
formation of a less stable carbonium ion in aryl halides
B
resonance stabilisation in aryl halides
C
presence of double bonds in alkyl halides
D
inductive effect in aryl halides
Answer :
resonance stabilisation in aryl halides