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CBSE Questions for Class 12 Engineering Chemistry Aldehydes,Ketones And Carboxylic Acids Quiz 7 - MCQExams.com
CBSE
Class 12 Engineering Chemistry
Aldehydes,Ketones And Carboxylic Acids
Quiz 7
Nucleophilic addition reaction will be most favoured in
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$$ CH_3 CH_2 CHO $$
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$$ CH_3 CHO $$
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$$ CH_3 CH_2 CH_2 -\overset { \overset { O }{ \parallel } }{ C } - CH_3 $$
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$$ (CH_3)_2C = 0 $$
Explanation
Nucleophilic addition reaction will be most favoured in the compounds with least electron density at CO bond.
Order of electron density at CO bond in the given compounds:
$$\mathrm{B<A<D<C}$$
So, Nucleophilic addition reaction will be most favored in $$\mathrm{CH_3CHO}$$.
Hence, Option "B" is the correct answer.
Which of the following gives nucleophilic addition reactions?
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Methanal
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Ethanal
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Propanone
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Propene
Explanation
All carbonyl compounds give nucleophilic addition reactions.
Of the above options, only propene is a alkene (electron-rich) does not give addition reaction rest all others give nucleophilic addition reaction.
Hence, Optiona "A", "B" & "C" are ccorrect answers.
$$C_7H_{16} \xrightarrow[\begin{matrix} 773K \\ 10\ atm\end{matrix} ]{\begin{matrix} Cr_2O_3\\Fe_2O_3\end{matrix}} A \xrightarrow{KMnO_4/H^{\oplus}}B$$
Then what is the incorrect statement?
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$$B$$ will give effervescence with $$NaHCO_3$$
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$$A$$ has degree of unsaturation equal to $$4$$
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$$B$$ with slaked lime gives a symmetrical ketone.
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None of these
Explanation
Option D is correct.
Which of the following is used as a hypnotic?
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Paraldehyde
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Metaldehyde
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Acetaldehyde
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Formaldehyde
Acetone+A $$ \rightarrow $$ oxime of acetone
Acetone+B $$ \rightarrow $$ diacetone amine
Acetone+C $$ \rightarrow $$ mesitylene
Acetone+D $$ \rightarrow $$ isopropylidene chloride A,B,C and D are:
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$$ NH_2OH,NH_3,Conc.H_2SO_4,SOCl_2 $$
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$$ HNO_2,NH_3,Conc.H_2SO_4,PCl_5 $$
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$$ HNO_2,NH_3,Conc.H_2SO_4,Cl_2 $$
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$$ NH_2OH,NH_3,H_2SO_4,Cl_2 $$
Which of the following is an example of nucleophilic addition to acetone?
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Ketal formation
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Reduction with hydrogen gas
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Cyanohydrin formation
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Bisulphite addition
Explanation
Ketal formation and
Reduction with hydrogen gas are examples of elimination reactions, whereas cyanohydrin formation and bisulphite addition are examples of nucleophilic addition reactions.
Hence, Options "C" & "D" are correct answers.
Which has minimum reactivity towards nucleophiles?
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Butanone
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Propanone
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Ethanal
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Methanal
Which of the following is not the functional isomer of monocarboxylic acid?
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Amide
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Ester
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Hydroxy aldehyde
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Hydroxy ketone
Explanation
Consider the acid : $$C_2H_5COOH$$ i.e $$C_3H_6O_2$$
(A) Amide : $$C_3H_7ON$$
(B) Ester: $$C_3H_6O_2$$
(C) Hydroxy Aldehyde: $$C_3H_6O_2$$
(D) Hydroxy Ketone: $$C_3H_6O_2$$
Hence option (A) is the answer.
Unknown compound $$(A)$$ on oxidation with hot basic $$KMnO_{4}$$ gives only one compound whose structure is given in the figure.
Compound $$(A)$$ will be:
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$$CH_{3} - C \equiv C - (CH_{2})_{4} - C \equiv C - CH_{3}$$
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$$CH_{3} - CH = CH - (CH_{2})_{4} - CH = CH_{2}$$
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$$CH_{3} - CH = CH - (CH_{2})_{4} - CH = CH - CH_{3}$$
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Monocarboxylic acids (saturated) are regarded as _____ oxidation products of paraffins.
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first
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second
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third
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fourth
Explanation
Monocarboxylic acids (saturated) are regarded as $$\textbf {third}$$ oxidation products of paraffins.
The formation of cyanohydrin from a ketone is an example of:
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electrophilic addition
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nucleophilic addition
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nucleophilic substitution
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electrophilic substitution
The IUPAC name of caproic acid is:
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pentanoic acid
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hexanoic acid
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heptanoic acid
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octanoic acid
Explanation
$$\textbf {Hexanoic acid}$$, also known as caproic acid, is the carboxylic acid derived from hexane with the chemical formula $$CH_3(CH_2)_4COOH.$$
Hence option (B) is correct.
Some carboxylic acids and their IUPAC names are given below. Which of the following is not correctly matched?
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Formic acid - Methanoic acid
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Acetic acid - Ethanoic acid
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Iso-butyric acid - 2 - Methyl butanoic acid
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Malonic acid - Propandioic acid
Explanation
Isobutyric acid is $$(CH_3)_2CHCOOH$$.
2 - Methyl butanoic acid is $$CH_3-CH_2-CH(CH_3)-COOH$$
hence option (C) is the answer.
Arrange the following compounds in increasing order of their reactivity in nucleophilic addition reactions:
Ethanal (I), Propanal (II), Propanone (III), Butanone (IV)
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$$I>III>IV>II$$
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$$I>II>III>IV$$
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$$III>II>I>IV$$
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$$II>IV>III>I$$
Paraldehyde is used as a:
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medicine
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poison
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polymer
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dye
Explanation
Uses for paraldehyde: $$medicinal\ use$$
Paraldehyde is $$\text{used to treat certain convulsive disorders.}$$ It also has been used in the treatment of$$ alcoholism$$ and in the treatment of $$nervous \ and \ mental \ conditions$$ to calm or relax patients who are nervous or tense and to produce sleep.
$$ (CH_3)_2CO \xrightarrow [HCl]{NaCN}(A) \xrightarrow [ \triangle]{H_3O^+ } (B) $$are :
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$$ (CH_3)_2C(OH)CN, (CH_3 )_2C(OH)COOH $$
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$$ (CH_3)_2C(OH)CN, (CH_3)_2C(OH)_2 $$
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$$ (CH_3)_2C(OH)CN, (CH_3)_2CHCOOH $$
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$$ (CH_3)_2C(OH)CN, (CH_3)_2CO $$
In the given reaction, product $$P$$ is:
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Explanation
$$RMgX(Grignard's \;Reagent) + CO_2/H^+ \rightarrow RCOOH$$
Hence (P) is $$C_6H_5-COOH$$
Hence option (B) is correct.
Which of the following gives smell of burnt sugar on charring?
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Oxalic acid
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Tartaric acid
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Malonic acid
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Succinic acid
Explanation
Tartaric acid on charring gives the smell of burning sugar.
Hence, Option "B" is the correct answer.
Best starting material to synthesize 2-methylpentan-2-ol is
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$${CH}_{3}{CH}_{2}{CH}_{2}CH_2CHO$$
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$$CH_3COOH$$
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Explanation
The easiest method to prepare 2-methylpentan-2-ol can be prepared by hydrolysis of Ethyl magnesium bromide with Butan-4-one.
Hence, Option "D" is the correct answer.
Which of the following reduces carboxylic acid directly to primary alcohols?
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$$LiAl{H}_{4}$$
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$$Na+{C}_{2}{H}_{5}OH$$
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$$Na{BH}_{4}$$
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$${H}_{2}$$
Nucleophilic addition reaction will be most favoured in:
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$$ CH_3CH_2CHO $$
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$$ CH_3CHO $$
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$$ (CH_3)_2 C=O $$
The synthesis of crotonaldehyde from acetaldehyde is an example of........... reaction.
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nucleophilic addition
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elimination
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electrophilic addition
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nucleophilic addition elimination.
Explanation
Crotanaldehyde is produced by the aldol condensation of acetaldehyde
crotanaldehyde
Aldehydes
are carbonyl molecules that have a carbon attached to oxygen with a double bond, another group, and a hydrogen atom. ...
Aldehydes
and ketones undergo
nucleophilic addition reactions
due to the polarity in the carbonyl bond that makes them vulnerable to a
nucleophile
, an atom that donates electrons.
In the reaction,
$${ C }_{ 2 }{ H }_{ 5 }OH\xrightarrow [ ]{ P{ I }_{ 3 } } (A)\xrightarrow [ ]{ KCN } (B)\xrightarrow [ ]{ Hydrolysis } (C)$$
The product (C) is:
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acetic acid
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formic acid
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oxalic acid
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propionic acid
An aldehyde can give nucleophilic addition reaction with:
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$$ HCN $$
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$$ NaHSO_3 $$
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$$ R-MG-X $$
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$$ NH_2NH_2 $$
Which of the following statements is not correct?
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Aldehydes and ketones contain polar carbonyl group
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Aldehydes and ketones undergo nucleophilic addition
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Aldehydes and ketones undergo electrophilic substitution
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Lower members of aldehydes and ketones are soluble in water due to hydrogen bonding
Which gives nucleophilic addition reactions?
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Methanal
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Ethanal
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Propanone
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None of these
Acetone gives addition elimination reaction with:
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$$ NH_2OH $$
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$$ NaHSO_3 $$
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$$ NH_2NHCONH_2 $$
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$$ NH_2NHC_6H_5 $$
Acetaldehyde reacts with both nucleophiles and electrophiles.
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True
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False
Explanation
Acetaldehyde reacts with both nucleophiles and
electrophiles because of presence of both electron deficient and electron rich sites in it.
The Carbon in -CHO group is electron deficient and Oxygen in -CHO group is electron-rich.
Hence, the given statement is True.
Which of the following compounds will give carboxylic acid with nitrous acid $$ (HNO_2)? $$
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R-COCl
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$$ R-CONH_2 $$
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R-COOR
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$$ (RCO)_2O $$
Explanation
$$RCONH_2 + HNO_2 \rightarrow RCOOH$$
Hence option (B) is correct.
Oil of vanilla bean is
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Explanation
Vanillin is an organic compound with the molecular formula $$C_8H_8O_3$$. It is a phenolic aldehyde. Its functional groups include aldehyde, hydroxyl, and ether. It is the primary component of the extract of the vanilla bean.
Option A is correct
The structures of the products $$Q$$ and $$R$$, respectively, are
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The structure of the carbonyl compound $$P$$ is
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Compound ' P ' of the following reaction sequence can be:
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A tripeptide $$x$$ on partial hydrolysis gave two dipeptides Cys-Gly and Glu-Cys.
Identify the tripeptide,
$$\overset{+}{N}H_3 - \overset{CH_2CH_2COOH\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!}{\overset{\!\!\!\!\!\!|}{CH}} - \underset{Glu-Cys}{\underset{\!O}{\underset{||}{C}}} - NH - \overset{CH_2 SH\!\!\!\!\!}{\overset{\!\!\!\!\!\!|}{CH}} - \underset{O}{\underset{||}{C}} - \overset{-}{O}$$
and
$$\overset{+}{N}H_3 - \overset{CH_2SH\!\!\!\!\!\!\!\!}{\overset{\!\!\!\!\!\!|}{CH}} - \underset{Cys-Gly}{\underset{\!O}{\underset{||}{C}}} - NH - CH_2 - \underset{O}{\underset{||}{C}} - \overset{-}{O}$$
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Glu-Cys-Gly
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Gly-Glu-Cys
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Cys-Gly-Glu
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Cys-Glu-Gly
Explanation
$$\overset{+}{N}H_3 - \overset{CH_2CH_2COOH\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!}{\overset{\!\!\!\!\!\!|}{CH}} - \underset{Glu-Cys}{\underset{\!O}{\underset{||}{C}}} - NH - \overset{CH_2 SH\!\!\!\!\!}{\overset{\!\!\!\!\!\!|}{CH}} - \underset{O}{\underset{||}{C}} - \overset{-}{O}$$
and
$$\overset{+}{N}H_3 - \overset{CH_2SH\!\!\!\!\!\!\!\!}{\overset{\!\!\!\!\!\!|}{CH}} - \underset{Cys-Gly}{\underset{\!O}{\underset{||}{C}}} - NH - CH_2 - \underset{O}{\underset{||}{C}} - \overset{-}{O}$$
The tripeptide is Glu - Cys - Gly
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Explanation
Malononitrile reacts with aldehydes following knoevenagel condensation reaction with the elimination of water molecule.
See the given figure.
Which of the following compounds will give acetic acid with $$KMnO_{4}/H^{\bigoplus }/\Delta $$?
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$$ CH_{3}-CHO $$
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$$ CH_{3}-CH=CH- CH_{3}$$
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$$ CH_{3}-C=C- CH_{3}$$
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$$ CH_{2}CH_{2}OH $$
Explanation
$$KMn{O}_{4}$$ is an oxidizing agent so it will convert aldehyde group into acid.
$$C{H}_{3}-CHO \xrightarrow[KMn{O}_{4}/{H}^{+}]{\Delta} \underset{\text{Acetic acid}}{C{H}_{3}=COOH}$$
The IUPAC name of the following compound is
$$HOOC-CH_{2}-CH_{2}-O-CH_{2}-CH_{2}-COOH$$
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3,2'-oxypropionic acid
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3,2'-oxybutanoic acid
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3,2'-dioxypropionic acid
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3,3'-oxypropionic acid
$$R - \overset{O}{\overset{||}{C}} - Cl \xrightarrow[conc. \,H_2SO_4]{NaN_3} \xrightarrow[]{CH_3 - Cl (1 \,eqvt.)} \underset{\left( \text{Major product} \right)}{P}$$
Hence, Product $$(P)$$ is:
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$$R - NH_2$$
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$$R - NH - CH_3$$
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$$R - \overset{O}{\overset{||}{C}} - NH - CH_3$$
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$$R - NH - \overset{O}{\overset{||}{C}} - CH_3$$
Explanation
Alkyl or aryl acyl chloride reacts with sodium azide to give acyl azides.
See the figure i.
The acyl azides undergo thermal decomposition to an isocyanate with loss of $$N_2$$ gas. The isocyanate then undergoes nucleophilic attack to yield a primary amine.
See the figure ii and ii.
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Explanation
Hydrolysis (complete) produces carboxylic acid from cyanide / nitriles.
So, correct answer is option $$A$$.
$$C_{4}H_{8}O_{2}$$ represents:
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an acid only
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an ester only
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an ketone only
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an acid and an ester also
Explanation
$$C_{4}H_{8}O_{2}$$ represents an acid only.
Product is
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Find the output
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Explanation
$$\bf{Hint:}$$ It is a base-induced disproportionation reaction.
$$\bf{Explanation:}$$
In this reaction, two moles of aldehyde react to give a molecule of carboxylic acid and another molecule of primary alcohol. It belongs to the class of nucleophilic substitution reactions. It is also known as
Cannizzaro Reaction.
$$\bf{Mechanism:}$$
$$\bf{Final \ answer:}$$
Option $$B$$
Which of the following compounds gives an explosive on decarboxylation?
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$$2,4,6-$$trinitrobenzoic acid
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$$2,4-$$dinitrobenzoic acid
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$$o-$$aminobenzoic acid
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$$o-$$hydroxy benzoic acid
Identify $$X$$
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Explanation
Answer $$C.$$ See the figure i.
Benzaldehyde undergoes cannizaro reaction with acetophenone in presence of a base. See the giver figure ii, ii and iv.
The product "A" in the above reaction is:
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The IUPAC name of
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2 - hydroxy - 4 - pentanone
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4 - keto - 2- pentanol
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2- oxo - 4 - pentanol
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4 - hydroxy - 2 - pentanone
Which of the following carboxylic acid is most acidic in character -
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o-methyl benzoic acid
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m-methyl benzoic acid
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p-methyl benzoic acid
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Benzoic acid
Explanation
Acidity $$\propto \cfrac{1}{+I}$$
Methyl group shows +I effect. Hence, Benzoic acid is the most acidic one.
Option D is correct.
Which of the following is/are more reactive towards nucleophilic addition reactions?
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$$CH_3COCH_3$$
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$$HCHO$$
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$$CH_3CHO$$
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$$C_2H_5CHO$$
Explanation
Propan-2-one contains two methyl groups and hence the positive inductive effect in this case is much higher leading to stabilization of the positive carbocation formed as an intermediate
Which of the following forms a stable hydrate
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$$C{H_3}COC{H_3}$$
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$$C{H_3}CHO$$
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$$C{l_3}CCHO$$
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$$HCHO$$
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