Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

Assertion is correct but Reason is incorrect

Both Assertion and Reason are incorrect

MCQ Questions for Class 12 Medical Chemistry Alcohols, Phenols And Ethers Quiz 8

The order of reactivity of the following alcohols towards dehydration is:

0%
$IV > I > II > III$
0%
$III > IV > II > I$
0%
$II > I > III > IV$
0%
$II > III > I > IV$

Explanation

Reactivity of alcohol towards dehydration is increased by the stability of the carbocation formed subsequently. Order of carbocation stability is :

$tertiary>secondary>primary.$

Also presence of

$+I$ groups like

$CH_3$ increases the stability.

According to this the order of reactivity is ,

$II>I>III>IV$

Which of the following is most reactive towards the acid-catalysed dehyydration?

Explanation

In acid catalysed reaction, the

$-OH$ group is removed and carbocation formation takes place. More stable the carbocation, more will be the reactivity for this reaction. Carbocation is stabilized by conjugation with double bond, and its stability is also in the order.

$tertiary>secondary>primary$

According to this, option

$C$ will be the most reactive.

Consider the following reaction :
The product Z is:

0%
benzene
0%
toluene
0%
benzaldehyde
0%
benzoic acid

Explanation

$\longrightarrow C_6H_5COOH$ (Benzoic acid)

So,D is correct answer.

1158391_1112901_ans_5e3d30f0779c482abb63c1568c70cfee.png

Phenol can be distinguished from ethanol by the reaction with :

0%
$Na$
0%
$Br_{2}/Water$
0%
Neutral $AlCl_{3}$
0%
$1$ and $2$

Explanation

Phenol can discharge the red colour of

$Br_2/Water$ while Ethanol cannot do the same.

$C_6H_5OH+Br_2/H_2O \rightarrow 2, 4, 6-Tribromophenol$

Hence, Option B is the correct answer.

$CH_{2} = CH_{2} + H_{2}SO_{4} \xrightarrow[]{75 - 80^{\circ}C} A \xrightarrow[warm]{H_{2}O} B$

$A$ and

$B$ in the above reaction are:

0%
$C_{2}H_{5}OH ; C_{2}H_{5}HSO_{4}$
0%
$(C_{2}H_{5})_{2}SO_{4} ; C_{2}H_{5}OH$
0%
$C_{2}H_{5}HSO_{4} ; C_{2}H_{5}OH$
0%
$C_{2}H_{5}OH ; (C_{2}H_{5})_{2}SO_{4}$

Phenol reacts with acetone in the presence of conc. Sulphuric acid to form a

${C}_{15}{H}_{16}{O}_{2}$ product. The structural formula of the product is:

0%
0%
0%
$X\begin{matrix} O-C_6H \\\!\!\!\!\!\!\!OC_6H_5 \end{matrix}$
0%

Phenol can be distinguished from ethanol by reactions with the following except:

0%
Iodine and alkali
0%
Ferric chloride
0%
Acetyl chloride
0%
Bromine water

Explanation

Option C is correct.
Both Phenol and Ethanol undergo esterification reaction with acetyl chloride. Hence, they cannot be distinguished by this test.

$C_2H_5-OH+CH_3COCl\rightarrow C_2H_5-O-CO-CH_3+ HCl$

$C_6H_5-OH+CH_3COCl\rightarrow C_6H_5-O-CO-CH_3+HCl$

In the following reaction

$Phenol \overset{Zn dust}{\rightarrow} X \xrightarrow[anh. Alcl_3]{CH_3Cl} Y \overset{alk.KMnO_4/\triangle}{\rightarrow} Z$
The product Z is:

0%
toulene
0%
benzaldehyde
0%
benzoic acid
0%
benzene

Explanation

Option C is the correct answer.
As we can see from the sequence of reactions,

$Z$ is Benzoic acid.

1104398_1121064_ans_ae9f9c4f6085404488ad8e5c2f7aca80.jpg

Identify Z in the given sequence of reaction.

$C-O-C$ bond in ethers can be cleaved by:

0%
${ H }_{ 2 }{ SO }_{ 4 }$
0%
${ LiAIH }_{ 4 }$
0%
$KOH$
0%
$HI$

Explanation

$C-O-C$ bond in ethers can be cleaved by

$H_2SO_4$ or conc.

$HI$ or

$LiAlH_4$

Mixed ether will not be formed in the reaction?

0%
$CH_3OCH_2Cl + C_2H_5MgBr$
0%
$CH_2N_2 + C_2H_5OH$
0%
$C_2H_5ONa + CH_3I$
0%
$C_2H_5OH + H_2SO_4 (140^0C)$

Explanation

Option D is the correct answer.

$C_2H_5-OH+H_2SO_4\ (140°C) \rightarrow C_2H_5-O-C_2H_5+H_2O$
Ethyl alcohol when heated with Sulphuric acid at 140°C produces a symmetric ether i.e. Diethyl ether.

In this reaction the product

$X$ is:

0%
$C_6H_5OC_2H_5$
0%
$C_2H_5OC_2H_5$
0%
$C_6H_5OC_6H_5$
0%
$C_6H_5I$

Explanation

Alkyl halides react with phenol to give the corresponding alkyl phenyl ether. So,

$C_4H_5I$ with phenol gives ethoxy benzene.
1380438_1121261_ans_1c63083c484f4b31b574da7da228273c.png

0%
$FeCl_{ 3 }$
0%
$NaOH$
0%
$NaNO_{ 2 }$
0%
Fehling's Solution .

Explanation

Option A is correct.
Phenol reacts with neutral

$FeCl_3$ to form a blue-violet coloured complex as shown in the figure.
No such reaction occurs in case of Toluene.
Thus,

$FeCl_3$ can differentiate between them.

1102186_1121959_ans_054188589afc454899f8e79b1a202bd9.png

Alcohol can be dehydrated by:

0%
$(C{ H }_{ 3 }CO{ ) }_{ 2 }O$
0%
$(C{ H }_{ 3 }{ ) }_{ 2 }S{ O }_{ 4 }$
0%
HI/P
0%
Anhy $ZnC{ l }_{ 2 }/\Delta$

Explanation

Option D is the correct answer.

$R-CH_2-OH \xrightarrow{Anhy\ ZnCl_2/\Delta} R=CH_2$

In an aqueous solution at

${25}^{o}C$ has twice as many

${OH}^{-}$ as pure water its

$pOH$ will be:

0%
$6.699$
0%
$7.307$
0%
$7$
0%
$6.98$

Explanation

Option

$A$ is the correct answer.
We know that pure water at 25°C has

$10^{-7} M$ of

$OH^-$ .
According to the problem, the aqueous solution at the same temperature has

$2 \times10^{-7}M$

$OH^-$

Therefore, its

$pOH = -log(2 \times10^{-7})$

$pOH = 6.6989$

$or, pOH = 6.699$

Phenol can be distinguished from ethyl alcohol by reagent except:

0%
NaOH
0%
$FeCl_{3}$
0%
$Br_{2}/H_{2}O$
0%
Na

Explanation

Phenol can discharge the red colour of

$Br_2/H_2O$ whereas Ethanol can't.

$C_6H_5-OH \overset{Br_2/H_2O}\rightarrow 2, 4, 6-tribromophenol$

Phenol also give a positive test with NaOH an

$FeCL_3$ .

Which of the following does not react with sodium hydroxide?

0%
Phenol
0%
Benzoic acid
0%
Acetic acid
0%
Benzophenone

Which of the following name does not fit a real name?

0%
$3$ -methyl $3$ -hexanone
0%
$4$ -methyl $3$ -hexanone
0%
$3$ -methyl $3$ -hexanol
0%
$2$ -methylcyclohexanone

What is the major product in the following reaction?

0%
o-bromophenol
0%
p-bromophenol
0%
2,4,6-tribromophenol
0%
m-bromophenol

Explanation

$CS_2\rightarrow$ Non polar solvent

$\rightarrow$ give

$O.p$ products.

Major will be para product.

B is the correct answer.

1175047_1136557_ans_0f013df5a1374cf3bd642e7cf619fd1f.PNG

Consider the following reaction:

$Phenol \xrightarrow [ Zn]{ dust } X \xrightarrow [ CH_3Cl ]{ Anhy. AlCl_3 } Y \xrightarrow [ KMnO_4 ]{ alkaline} Z$

the product Z is :

0%
Benzaldehyde
0%
Benzoic acid
0%
Benzene
0%
Toluene

Explanation

Option B is the correct answer.

It is evident from the sequence of reactions, that

$Z$ is Benzoic acid.

1104563_1133256_ans_16c289552e30488688e892b42a001ecb.png

In the reaction

$ROH+PBr_{3} \rightarrow RBr$
The number of moles of alcohol that may be converted into alkyl bromide by one mole of

$PBr_{3}$ is:

0%
$1$ mole
0%
$2$ mole
0%
$3$ mole
0%
none of the above

Explanation

From the balanced chemical equation,

$1$ mole of

$ROH$ reacts with

$1$ mole of

$PBr_3$ to form

$1$ mole of

$RBr$

Example:

$3CH_3CH_2OH +PBr_3\xrightarrow{P+Br_2} 3CH_3CH_2Br + H_3PO_3$

By which of the following methods alcohol can be prepared in excellent yield ?

0%
From alkenes
0%
By hydroboration-oxidation
0%
From carbonyl compounds
0%
From Grignard reagent

Which of the following alcohols will react with

${H}^{+}$ with greatest ease?

Phenol on heating with

${NaNO}_{2}$ and a few drops of concentrated sulphuric acid mainly gives:

0%
Para nitrophenol
0%
Para nitrosophenol
0%
Ortho nitrophenol
0%
Meta nitrophenol

Structure of

$C_3H_7Br$ should be

0%
0%
0%
Both of these
0%
None of these

Predict the major products (A) and (B).

Explanation

On treatment of

$OMDM$ ,the product will be trans and cis. But when treated by

${ H }_{ 3 }{ O }^{ \oplus }$ ion it will not produce cis trans product.
1137159_1198848_ans_9c430bec04114f06a45f281fd5848e1f.png

In the reaction, the product

$A$ is:

The homologue of phenol is:

Explanation

Two compound are said to be homologue to each other if the difference between their atomic mass is equal to 14 unit or

$-CH_{2}$ unit difference is present.

1188082_1179355_ans_3e9ececae56c4c08bf42b4226e4f0cc5.jpg

The phenol having lowest acidity is

Which of the following is a secondary alcohol ?

0%
0%
0%
0%
${ CH }_{ 3 }OH\quad$

Explanation

Alcohols can be classified as primary, secondary or tertiary on the basis of the nature of the carbon to which the OH group is attached. This carbon is called carbinol carbon.

Primary alcohol - The carbinol carbon is attached to only one other carbon atom. Example: 1-hexanol

Secondary alcohol – The carbinol carbon is attached to two other carbon atoms. Example: 2-hexanol

Tertiary alcohol - The carbinol carbon is attached to three other carbon atoms. Example: 2-methyl-2-pentanol

$(CH_3)_2CH-OH$ Option B is a secondary alcohol.

Whereas Option A is a primary alcohol, Option C is tertiary alcohol, Option D is a primary alcohol

Option B is the correct answer.

Benzene can be obtained by heating either benzoic acid with X or phenol with Y. X and Y respectively are

0%
Zinc dust and soda lime
0%
Soda lime and zinc dust
0%
Zinc dust and sodium hydroxide
0%
Soda-lime and copper

Molecule which does not oxidise using PCC?

The IUPAC name of the following compound is :

$CH_3 - \overset{CH_3\!\!\!\!\!}{\overset{|}{CH}} - \overset{O}{\overset{||}{C}} - CH_2 - CH_2 OH$

0%
$1$ -hydroxy- $4$ -methylpentan- $3$ -one
0%
$2$ -methyl- $5$ -hydroxypentan- $3$ -one
0%
$4$ -methyl- $3$ -oxopentan- $1$ -ol
0%
hexan- $1$ -ol- $3$ -one

Which compound is formed when a mixture of calcium acetate and calcium formate if heated ?

0%
$H_3C-\overset{O}{\overset{||}{C}}-CH_3$
0%
$H_3C-\overset{O}{\overset{||}{C}}-O-C-CH_3$
0%
$HCHO$
0%
$H_3C-CHO$

Write the IUPAC name of the following compounds.

0%
1-methoxy-3-nitrocyclohexane
0%
3-methoxy-1-nitrocyclohexane
0%
1-nitro-3-methoxycyclohexane
0%
3-nitro-1-methoxycyclohexane

In which of the following substances, ethanol is not used?

0%
Tonics
0%
Cough mixture
0%
Candle
0%
Alcohol

Ethene on reaction with cold & dilute alkaline

$KMnO_4$ gives ?

0%
Ethylene glycol
0%
Propylene glycol
0%
Acetone
0%
Alcohol

Give the IUPAC name of the above compound.

0%
2-Bromo 3-methyl butyric acid
0%
2-Bromo 4-formyl butane
0%
3-Bromo 2-methyl butanoic acid
0%
None of the above

But-2-ene can be obtained by reacting:

0%
1,2-dibromopropane with zinc
0%
Ethyl bromide with sodium
0%
Ethylidene bromide with zinc
0%
n-butyl alcohol with alcoholic KOH

Which of the following combinations can be used for the preparation of cis vic diol?

0%
Alkene, Baeyer reagent
0%
Alkene , $OsO_{4}$
0%
Alkene, MMPP and $H_{2}O/H$
0%
Both of (A) and (B)

Which of the following ether is unlikely to be cleaved by hot cone. HBr.

$3-methyl-1-butene$ on oxymercuration -demercuration yields________ as the major product

0%
$3-methyl-2-butanol$
0%
$2-methyl-2-butanol$
0%
$3-methyl-1-butanol$
0%
$2-methyl-1-buranol$

The compound formed on hydroysis of the adduct of methyl magnesium iodide and benzaldehyde:

0%
is a phenol.
0%
gives iodoform test.
0%
is a primary alcohol.
0%
gives benzophenone on oxidation.

Find the product :

0%
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
0%
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
0%
Assertion is correct but Reason is incorrect
0%
Both Assertion and Reason are incorrect

When the reaction between methyl iodide and sodium ethoxide occurs, we get:

0%
methyl acetate
0%
ethyl methyl ketone
0%
ethyl acetate
0%
ethyl methyl ether

Ethene reacts with

$Y$ to produce ethanol.

$ethene + Y \rightarrow ethanol$
What is

$Y$ ?

0%
Hydrogen
0%
Oxygen
0%
Steam
0%
Yeast

Explanation

Solution:- (C) Steam

Ethanol can be manufactured by hydration of ethene.

Ethene is heated with steam in the presence of a catalyst of phosphoric acid to produce ethanol.

${C}_{2}{H}_{4} + {H}_{2}O \xrightarrow{\text{high temperature}} \underset{\left( \text{Ethanol} \right)}{{C}_{2}{H}_{5}-OH}$

Hence

$Y$ is steam.

Correct order of acidic strength.

0%
$I > II > III$
0%
$II > III > I$
0%
$I > III > II$
0%
$III > II > I$

Explanation

Acidic nature

$\alpha - I$ .
1273915_1630428_ans_1eabeaaa7b6341cc89528ee93adcdd91.jpg

Which one of the following compounds is most acidic?

0%
phenol
0%
Trichoroacetaldeyde
0%
Trichloroacetic acid
0%
Benzoic acid

Three chemical reactions are shown.
1 catalytic addition of steam to ethene
2 combustion of ethanol
3 fermentation of glucose
In which of the reactions does the relative molecular mass of the carbon-containing compound
decrease?

0%
$1$ and $2$
0%
$1$ only
0%
$2$ and $3$
0%
$3$ only

CBSE Questions for Class 12 Medical Chemistry Alcohols, Phenols And Ethers Quiz 8 - MCQExams.com

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Practice Class 12 Medical Chemistry Quiz Questions and Answers

CBSE Questions for Class 12 Medical Chemistry Alcohols, Phenols And Ethers Quiz 8 - MCQExams.com

0:0:1

Practice Class 12 Medical Chemistry Quiz Questions and Answers

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