Electrophilic Aromatic Substitution (Haloalkanes and Haloarenes) MCQ Questions & Answers in Organic Chemistry | Chemistry
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191.
Identify the compound $$'Y'$$ in the following reaction.
A
B
C
D
Answer :
This is Sandmeyer's reaction and the product $$Y$$ is chlorobenzene.
192.
When $$C{H_3}C{H_2}CHC{l_2}$$ is treated with $$NaN{H_2},$$ the product formed is
193.
Chloroform is kept in dark coloured bottles because
A
it reacts with clear glass
B
it undergoes chlorination in transparent glass bottles
C
it is oxidised to poisonous gas, phosgene in sunlight
D
it starts burning when exposed to sunlight
Answer :
it is oxidised to poisonous gas, phosgene in sunlight
Chloroform gets oxidised by air in sunlight to poisonous phosgene gas.
\[2CHC{{l}_{3}}+{{O}_{2}}\xrightarrow{h\nu }\underset{\text{Phosgene}}{\mathop{2COC{{l}_{2}}+2HCl}}\,\]
194.
The increasing order of the reactivity of the following halides for the $${S_N}1$$ reaction is
A
(III) < (II) < (I)
B
(II) < (I) < (III)
C
(I) < (III) < (II)
D
(II) < (III) < (I)
Answer :
(II) < (I) < (III)
Since $${S_N}1$$ reactions involve the formation of carbocation as intermediate in the rate determining step, more is the stability of carbocation higher will be the reactivity of alkyl halides towards $${S_N}1$$ route. Since stability of carbocation follows order.
Hence correct order is (II) < (I) < (III)
The correct order of increasing bond length is $$C{H_3}F < C{H_3}Cl < C{H_3}Br < C{H_3}I$$
198.
Match the reactions given in column I with the type of reaction mentioned in column II and mark the appropriate choice.
A
A - iv, B - i, C - ii, D - iii
B
A - ii, B - iii, C - iv, D - i
C
A - i, B - ii, C - iv, D - iii
D
A - iii, B - i, C - ii, D - iv
Answer :
A - ii, B - iii, C - iv, D - i
No explanation is given for this question. Let's discuss the answer together.
199.
The missing reagents $${R_1}$$ and $${R_2}$$ in the following series of reactions are \[C{{H}_{3}}C{{H}_{2}}Br\xrightarrow{{{R}_{1}}}\left[ \,\,\,\, \right]\xrightarrow{{{R}_{2}}}C{{H}_{3}}\overset{-}{\mathop{C}}\,H{{P}^{+}}P{{h}_{3}}\]
A
$$A$$ on reaction with $$aq.\,KOH$$ gives $$HOC{H_2}C{H_2}COOK$$
B
$$B$$ can be resolved into $$d–$$ and $$l-$$ forms
C
Both (A) and (B)
D
Neither (A) nor (B)
Answer :
Both (A) and (B)
The compound $$A$$ is
\[C{{l}_{3}}C.C{{H}_{2}}C{{H}_{2}}Cl\xrightarrow{aq.\,KOH}{{\left( OH \right)}_{3}}C.C{{H}_{2}}C{{H}_{2}}OH\xrightarrow{-2{{H}_{2}}O}HO\,C{{H}_{2}}.C{{H}_{2}}COOK.\]
The compounds $$B$$ is has chiral centre and can be resolved into $$d-$$ and $$l-$$ form.