Electrophilic Aromatic Substitution (Haloalkanes and Haloarenes) MCQ Questions & Answers in Organic Chemistry | Chemistry
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141.
The main difference in $$C - X$$ bond of a haloalkane and a haloarene is
A
$$C - X$$ bond in haloalkanes is shorter than haloarenes.
B
in haloalkanes the $$C$$ attached to halogen in $$C - X$$ bond is $$s{p^3}$$ hybridised while in haloarenes it is $$s{p^2}$$ hybridised.
C
$$C - X$$ bond in haloarenes acquires a double bond character due to higher electronegativity of $$X$$ than haloalkanes.
D
haloalkanes are less reactive than haloarenes due to difficulty in $$C - X$$ cleavagein haloalkanes.
Answer :
in haloalkanes the $$C$$ attached to halogen in $$C - X$$ bond is $$s{p^3}$$ hybridised while in haloarenes it is $$s{p^2}$$ hybridised.
In haloarenes, carbon of $$C - X$$ is $$s{p^2}$$ hybridised while in haloalkanes it is $$s{p^3}$$ hybridised.
142.
The following reaction proceeds through the intermediate formation of
$$RCOOAg + B{r_2} \to RBr + C{O_2} + AgBr$$
143.
Haloalkanes contain halogen atom$$(s)$$ attached to the $$s{p^3}$$ hybridised carbon atom of an alkyl group. Identify haloalkane from the following compounds.
(i) 2-Bromopentane
(ii) Vinyl chloride
(iii) 2-Chloroacetophenone
(iv) Trichloromethane
A
(ii) only
B
Only (ii) and (iv)
C
Only (i) and (iv)
D
Only (i), (ii) and (iii)
Answer :
Only (i) and (iv)
No explanation is given for this question. Let's discuss the answer together.
144.
Match the column I with column II and mark the appropriate choice.
A
A - iv, B - ii, C - i, D - iii
B
A - iii, B - iv, C - ii, D - i
C
A - ii, B - i, C - iii, D - iv
D
A - i, B - iii, C - iv, D - ii
Answer :
A - iii, B - iv, C - ii, D - i
No explanation is given for this question. Let's discuss the answer together.
145.
Which is the correct increasing order of boiling points of the following compounds?
1-Iodobutane, 1-Bromobutane, 1-Chlorobutane, Butane
A
Butane < 1-Chlorobutane < 1-Bromobutane < 1-Iodobutane
B
1-Iodobutane < 1-Bromobutane < 1-Chlorobutane < Butane
C
Butane < 1-Iodobutane < 1-Bromobutane < 1-Chlorobutane
D
Butane < 1-Chlorobutane < 1-Iodobutane < 1-Bromobutane
For the same alkyl halide, boiling point increases as the mass of halogen increases.
146.
Which of the following compounds can yield only one monochlorinated product upon free radical chlorination?
A
2, 2-Dimethylpropane
B
2-Methylpropane
C
2-Methylbutane
D
$$n$$ - Butane
Answer :
2, 2-Dimethylpropane
All the hydrogen atoms in 2, 2-dimethyl-propane are equivalent, hence it can form only one mono chlorinated product.
147.
The Wurtz-Fittig reaction involves condensation of
A
two molecules of aryl halides.
B
one molecule of each of aryl-halide and alkyl-halide.
C
one molecule of each of aryl-halide and phenol.
D
two molecules of aralkyl-halides.
Answer :
one molecule of each of aryl-halide and alkyl-halide.
Reaction between alkyl halide, aryl halide and sodium in presence of ether is known as Wurtz fitting reaction
$${C_6}{H_5}Cl + 2Na + ClC{H_3} \to \mathop {{C_6}{H_5}C{H_3}}\limits_{{\text{Toluene}}} + 2NaCl$$
148.
The correct product obtained in the reaction
A
B
C
D
Answer :
In $${2^ \circ }$$ halides of this type the product formed has inverted configuration ( $${S_N}2$$ mechanism ).
149.
A mixture of 1-chloropropane and 2-chloropropane when treated with alcoholic $$KOH$$ gives
A
prop-1-ene
B
prop-2-ene
C
a mixture of prop-1-ene and prop-2-ene
D
propanol
Answer :
prop-1-ene
150.
Which of the following reactions is not correctly matched?
A
\[2{{C}_{2}}{{H}_{5}}Br+2Na\xrightarrow{\text{dry}\,\,\text{ether}}\] \[{{C}_{4}}{{H}_{10}}+2NaBr\,;\,\text{Wurtz reaction }\]
B
\[C{{H}_{3}}Br+AgF\to C{{H}_{3}}F+AgBr\,;\] \[\text{Etard reaction }\]
C
\[{{C}_{6}}{{H}_{5}}Br+2Na+Br{{C}_{2}}{{H}_{5}}\xrightarrow{\text{dry}\,\,\text{ether}}\] \[{{C}_{6}}{{H}_{5}}{{C}_{2}}{{H}_{5}}+2NaBr\,;\] \[\text{Wurtz-Fittig reaction}\]
D
\[2{{C}_{6}}{{H}_{5}}Br+2Na\xrightarrow{\text{dry}\,\,\text{ether}}\] \[{{C}_{6}}{{H}_{5}}-{{C}_{6}}{{H}_{5}}+2NaBr\,;\] \[\text{Fittig reaction}\]