Aldehyde and Ketone MCQ Questions & Answers in Organic Chemistry | Chemistry
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191.
Acetone reacts with iodine $$\left( {{I_2}} \right)$$ to form iodoform in the presence of
A
$$CaC{O_3}$$
B
$$NaOH$$
C
$$KOH$$
D
$$MgC{O_3}$$
Answer :
$$NaOH$$
192. \[\xrightarrow{N{{H}_{2}}OH}\left( A \right)\xrightarrow{{{H}^{+}}}\left( B \right)\] \[\xrightarrow{LAH}\left( C \right);\] product $$(C)$$ of the reaction is :
A
B
C
D
Answer :
193.
Which of the following pairs of reactants is most effective in forming an enamine ?
A
B
C
D
Answer :
\[{{2}^{\circ }}\] amine must be less sterically hindered. In option (B) and (C) \[{{2}^{\circ }}\] amine is being used but due to more reactivity of aldehyde compared to cyclohexanone. Option (C) is correct.
194. \[\xrightarrow{PCC}\left( A \right)\xrightarrow[\Delta ]{dil.\,NaOH}\left( B \right)\]
Product $$(B)$$ is :
A
B
C
D
Answer :
195.
In the following sequence of reactions :
\[\text{Toluene}\xrightarrow{KMn{{O}_{4}}}A\xrightarrow{SOC{{l}_{2}}}B\xrightarrow[BaS{{O}_{4}}]{{{H}_{2}}/Pd}C\]
the product C is :
A
$${C_6}{H_5}C{H_2}OH$$
B
$${C_6}{H_5}CHO$$
C
$${C_6}{H_5}COOH$$
D
$${C_6}{H_6}C{H_3}$$
Answer :
$${C_6}{H_5}CHO$$
196.
Acetone is treated with excess of ethanol in the presence of hydrochloric acid. The product obtained is
A
B
C
D
Answer :
When carbonyl compounds are treated with alcohol, they form hemiacetal ( hemiketal and acetal/ketal. ) NOTE
Formation of hemiketal is a nucleophilic addition reaction.
197.
Among the following the order of reactivity towards nucleophilic addition is
A
$$C{H_3}CHO > C{H_3}COC{H_3} > HCHO$$
B
$$HCHO > C{H_3}CHO > C{H_3}COC{H_3}$$
C
$$C{H_3}CHO > HCHO > C{H_3}COC{H_3}$$
D
$$C{H_3}COC{H_3} > C{H_3}CHO > HCHO$$
Answer :
$$HCHO > C{H_3}CHO > C{H_3}COC{H_3}$$
Presence of alkyl group in carbonyl compounds decreases their reactivity towards nucleophilic addition. Further greater the number of such groups lesser will be the reactivity towards nucleophilic addition ∴ correct order is
$$HCHO > C{H_3}CHO > C{H_3}COC{H_3}$$
198.
Which one of the statements about $$HO{H_2}CCH\left( {OH} \right)CHO$$ is not correct? It
A
is an isomer of 1, 3-dihydroxypropanone
B
contains a tertiary alcoholic group
C
has the same empirical formula as glucose
D
can show optical isomerism
Answer :
contains a tertiary alcoholic group
\[\underset{\begin{smallmatrix}
|\,\,\,\, \\
\,\,\,\,\,\,C{{H}_{2}}OH
\end{smallmatrix}}{\overset{\begin{smallmatrix}
\,\,\,CHO \\
|\,\,\,\,
\end{smallmatrix}}{\mathop{H-C-OH}}}\,\]
It contains one primary and one secondary alcoholic group thus, option (B) is incorrect.
199.
Propanal on reaction with dilute $$NaOH$$ forms
A
$$C{H_3}C{H_2}C{H_2}C{H_2}C{H_2}CHO$$
B
$$C{H_3}C{H_2}CH\left( {OH} \right)C{H_2}C{H_2}CHO$$
C
$$C{H_3}C{H_2}C{H_2}CH\left( {OH} \right)C{H_2}CHO$$
D
$$C{H_3}C{H_2}CH\left( {OH} \right)CH\left( {C{H_3}} \right)CHO$$
Note that it is the $$\alpha $$ - carbon ( and not $$\beta - $$ ) that is adding on the carbonyl oxygen of the other propanal molecule.
200.
\[\left( X \right){{C}_{4}}{{H}_{7}}OCl\xrightarrow{N{{H}_{3}}}{{C}_{4}}{{H}_{9}}OH\] \[\xrightarrow[KHO]{B{{r}_{2}}}C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}N{{H}_{2}};\] compound $$(X)$$ is :