Learn Carboxylic Acid MCQ questions & answers in Organic Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
111.
In a set of the given reactions, acetic acid yielded a product $$C.$$
$$C{H_3}COOH + PC{l_5} \to $$ \[A\xrightarrow[anhy.\ AlC{{l}_{3}}]{{{C}_{6}}{{H}_{6}}}B\xrightarrow[\text{Ether}]{{{C}_{2}}{{H}_{5}}MgBr}C\]
Product $$C$$ would be
112.
An ester is boiled with $$KOH.$$ The product is cooled and acidified with concentrated $$HCl.$$ $$A$$ white crystalline acid separates. The ester is
A
methyl acetate
B
ethyl acetate
C
ethyl formate
D
ethyl benzoate
Answer :
ethyl benzoate
Ethyl benzoate on hydrolysis gives benzoic acid which is a solid, other esters give \[C{{H}_{3}}COOH\] and \[HCOOH,\] both of which are liquids.
113.
Which of the following statements is correct regarding formic acid?
A
It is a reducing agent.
B
It is a weaker acid than acetic acid.
C
It is an oxidising agent.
D
When its calcium salt is heated, it forms acetone.
Answer :
It is a reducing agent.
No explanation is given for this question. Let's discuss the answer together.
114.
Which of the following represents the correct order of acidity in the given compounds?
A
$$FC{H_2}COOH > C{H_3}COOH$$ $$ > BrC{H_2}COOH > ClC{H_2}COOH$$
B
$$BrC{H_2}COOH > ClC{H_2}COOH$$ $$ > FC{H_2}COOH > C{H_3}COOH$$
C
$$FC{H_2}COOH > ClC{H_2}COOH$$ $$ > BrC{H_2}COOH > C{H_3}COOH$$
D
$$C{H_3}COOH > BrC{H_2}COOH$$ $$ > ClC{H_2}COOH < FC{H_2}COOH$$
The acidity of halogenated acid increases with increase in electronegativity of the halogen present. The electronegativity of halogen decreases in order as $$F > Ce > Br.$$ Therefore correct order of given compounds is
$$FC{H_2}COOH > ClC{H_2}COOH > BrC{H_2}COOH > C{H_3}COOH$$
115.
In the Cannizzaro reaction given below,
\[2PhCHO\xrightarrow{^{-}OH}PhC{{H}_{2}}OH+PhCO_{2}^{-},\]
the slowest step is
A
the attack of $$^ - OH$$ at the carbonyl group,
B
the transfer of hydride to the carbonyl group,
C
the abstraction of proton from the carboxylic acid,
D
the deprotonation of $$PhC{H_2}OH.$$
Answer :
the transfer of hydride to the carbonyl group,
The possible mechanism is
NOTE : The slowest step is the transfer of hydride to the carbonyl group as shown in step (ii).
116.
A liquid was mixed with ethanol and a drop of concentrated $${H_2}S{O_4}$$ was added. A compound with a fruity smell was formed. The liquid was :
A
$$HCHO$$
B
$$C{H_3}COC{H_3}$$
C
$$C{H_3}COOH$$
D
$$C{H_3}OH$$
Answer :
$$C{H_3}COOH$$
Fruity smell is due to ester formation which is formed between ethanol and acid.
\[C{{H}_{3}}COOH+{{C}_{2}}{{H}_{5}}OH\xrightarrow{Conc.\,\,{{H}_{2}}S{{O}_{4}}}C{{H}_{3}}COO{{C}_{2}}{{H}_{5}}+{{H}_{2}}O.\]
117.
Schotten-Baumann reaction is a reaction of phenols with
120.
Which of the following acids has the smallest dissociation constant ?
A
\[C{{H}_{3}}CH\left( F \right)COOH\]
B
\[FC{{H}_{2}}C{{H}_{2}}COOH\]
C
\[BrC{{H}_{2}}C{{H}_{2}}COOH\]
D
\[C{{H}_{3}}CH\left( Br \right)COOH\]
Answer :
\[BrC{{H}_{2}}C{{H}_{2}}COOH\]
Bromine is less electronegative than $$F,$$ further in \[BrC{{H}_{2}}C{{H}_{2}}COOH,\] $$Br$$ is more away from the $$–COOH$$ group than in group than in \[C{{H}_{3}}CHBrCOOH.\]