MCQ Questions for Class 12 Engineering Chemistry Alcohols,Phenols And Ethers Quiz 6

Product of the reaction is :

Explanation

$H$ and $OH$ added are in a cis configuration. Since this is syn hydration, it follows Anti-Markovnikov's Rule.

1099324_989649_ans_72ea4fbb15ba418b8d21b02849a69250.PNG

How many moles of

$BH_3$ are needed to react completely with 2 moles of 1-pentene in hydroboration-oxidation reaction?

0%
2 moles
0%
3 moles
0%
2/3 moles
0%
3/2 moles

Explanation

$3$ moles of

$BH_3$ reacts completely with

$1$ mole of the alkene.

Now for 2 moles of an alkene, we require

$\dfrac23$ moles of

$BH_3$ .

Propene

$CH_{3} - CH = CH_{2}$ can be converted into

$1$ -propanol by oxidation. Indicate which sets of reagents amongst the following is ideal to effect the above conversion?

0%
$KMnO_{4}$ (alkaline)
0%
Osmimum tetroxide $(OsO_{4}/CH_{2}Cl_{2})$
0%
$B_{2} H_{6}$ and alk $H_{2}O_{2}$
0%
$O_{3}$ and $Zn/H_{2}O$

Explanation

$CH_3-CH=CH_2\xrightarrow[]{B_2H_6}CH_3-\underset{H}{\underset{|}{C}}H-\underset{BH_2}{\underset{|}{C}H_2}\xrightarrow[]{H_2O_2} CH_3-CH_2-CH_2OH$

This reaction is called as hydroboration-oxidation.

Product of the reaction is :

Explanation

As refer to the above image addition reaction resulting in formation of diols. Here,

$OsO_4/NaHSO_3$ is the reagent used which occurs in a syn manner.

1095692_989548_ans_706b878f052043589f8dcd31e6045c7f.png

$CH_3-CH_2-CH_2-CH_2- \overset{CH_3}{\overset{|}{\underset{CH_3}{\underset{|}{C}}}}-CH_2-CH_2-OH\xrightarrow[\Delta]{H^+}\underset{(major)}{(A)}$
Product (A) is:

0%
$CH_3-CH_2-CH_2-CH_2-\underset{CH_3}{\underset{|}{C}}=CH-CH_3$
0%
$CH_3-(CH_2)_3-C(CH_3)=C(CH_3)_2$
0%
$CH_3-CH_2-CH_2-CH_2-\underset{CH_3}{\underset{|}{C}}=CH_2$
0%
$CH_3-CH_2-\underset{CH_3}{\underset{|}{CH}}-CH_2-\overset{CH_3}{\overset{|}{C}}=CH_2$

Trans - cyclohexane -1,2- diol can be obtained by the reaction of cyclohexene with :

0%
$KMnO_4$
0%
$OsO_4$
0%
peroxy formic acid / $H_3 O^+$
0%
$SeO_2$

Energy profile diagram for dehydration of 2-butanol using conc.

$H_2SO_4$ is given below.
Product (b) of above reaction is :

0%
1-butene
0%
cis-2-butene
0%
trans-2-butene
0%
iso-butene

Explanation

From energy profile

$Me-CH_2-\overset{+}{CH}-CH_3$ has the least energy while means it is most stable molecule. Hence, dehydration of 2-Butanol forms

$Me-CH_2-\overset{CH}-CH_3$ which on dehydrogenation gives

$Me-CH=Ch-CH_3$ (A is molecule)

Based on above isomers answer the following.

Which isomers on dehydration with conc.

$H_2SO_4$ give alkene which is capable to show geometrical isomerism?

0%
g, h, f
0%
b, d, a
0%
a, b, c.
0%
None of these

Based on above isomers answer the following.

Which isomer on dehydration with conc.

$H_3PO_4$ undergo maximum rearrangement?

0%
a
0%
c
0%
e
0%
b

Explanation

Rearrangement keeps occurring until the carbocation formed is stable.

Stability order

$3^o>2^o>1^o$

Hence, option

$C$ is correct.

1120096_991902_ans_62f963bf0abc433295318b69d5da864d.PNG

Which of the following procedures would be best for the preparation of phenyl benzyl ether?

$C_6H_5OCH_2C_6H_5$ .

0%
$C_6H_5Cl+C_6H_5H_2O^{(-)}Na^{(+)}$
0%
$C_6H_5O^{(-)}Na^{(+)}+C_6H_5CH_2Cl$
0%
$2C_6H_5Cl+Na_2O$
0%
$2C_6H_5MgBr+CH_2O$

An organic compound having the molecular formula

$C_8H_{10}O$ on being heated with

$I_2$ and dilute NaOH gives a yellow precipitate. The expected compound is?

0%
$C_6H_5CH_2CH_2OH$
0%
0%
0%

Explanation

organic compound with the molecular formula of

$C_8H_{10}O$ which on being heated with

$I_2$ and dilute

$NaOH$ gives a yelow precipitate is in the diagram.
basically acetyle group

$CH_3-C=O$ containing compounds and

$CH_3-CH-OH$ group containing compounds will give yellow ppt.(

$CHI_3$ iodoform) with

$I_2$ and

$OH$ . this is iodoform test.

Final product

$A$ is:

0%
0%
$CH_{2} = C = CH_{2}$
0%
0%

Explanation

Refer to Image

This is pinacol reaction. This reaction occurs in presence of Conc.

$H_2SO_4$ (acidic medium). Adjacent diols under goes this reaction.

1074799_992354_ans_14bbe8168e49475685c2f321a10e8ac7.png

Select the best method for the preparation of the following compounds :

0%
reaction of cyclohexanone with $CH_{3}Li$
0%
reaction of $1-$ methylcyclohexene with $Hg(OAc)_{2}$ followed by $NaBH_{4}$
0%
reaction of cyclohexene with $BH_{4} ; NaOH/H_{2}O_{2}$ , followed by $CH_{3}Br$
0%
reaction of cyclohexene with $MCPBA$ , followed by $CH_{ 3 }MgBr$

Explanation

$MCPBA$ (Meta-chloro perbenzoic acid) is used as an oxidizing agent to produce epoxides. Grignard reagents are used to produce alcohols from epoxides.

The structure of the product formed in the reaction given below is :

$A$ &

$B$ respectively:

Explanation

Refer to Image.

Firstly hydroxylation reaction occurs in presence of

$H_2O_2$ to give syn-diol then, Pinacol-pinacolone reaction occurs in an acidic medium in which ring expansion occurs.

1074752_992271_ans_789c3c2358e840d8826b19d8552d4701.png

The IUPAC name of the compound is:

0%
$3$ - Ethylbutane - $2, 4$ - diol
0%
$2$ - Ethylbutane - $1, 3$ - diol
0%
$3$ - Ethylbutane - $1,3$ - diol
0%
$2$ - Ethyl - $1$ - methylpropane - $1, 3$ - diol

Explanation

IUPAC name of the given compound is: $2-Ethylbutane-1, 3-diol$

1068941_996346_ans_895e49381014440cbf5aadb41a3d6292.PNG

Based on above isomers answer the following.

Which isomer is most reactive towards dehydration by conc.

$H_2SO_4$ ?

0%
a
0%
d
0%
f
0%
g

Explanation

A compound is easily dehydated using

$H_2SO_4$ it forms a highly stable product double bond must be stabilised well by the alkyl group.
1380657_991890_ans_f6087eba4c8c4f9d8e125bf015b1dccf.png

1380657_991890_ans_f6087eba4c8c4f9d8e125bf015b1dccf.png

$CH_3 - CH_2 - OH\mathop \to \limits^{PCl_3 } P\mathop \to \limits_\Delta ^{alc.KOH} Q$
'Q' is:

0%
$H_2 C = CH_2$
0%
$CH_3 - CH_2 - OH$
0%
0%
$CH_3 - CH_2 - Cl$

Explanation

$CH_3-CH_2-OH\longrightarrow CH_3-CH_2-Cl\longrightarrow CH_2=CH_2+HCl$

chlorination reaction followed by elimination.

The IUPAC name of the following compound is: cyclopenta-1, 3-dien-1-ol

0%
True
0%
False

Explanation

It is fire membered ring.

Numbering will start from

$C$ attach to

$-OH$ group.

So,its name will be Cyclopenta-

$1,3-$ dien

$-1-$ ol

The product of acid catalyzed hydration of

$2-phenylpropene$ is:

0%
$3-phenyl-2-propanol$
0%
$1-phenyl-2-propanol$
0%
$2-phenyl-2-propanol$
0%
$2-phenyl-1-propanol$

Predict the correct option for major product.

0%
Major product is an alcohol bearing two deuterium atoms per molecule
0%
Major product is alcohol bearing one deuterium atom per molecule
0%
Major product is an alkane bearing two deuterium atoms per molecule
0%
Major product is an alkane bearing one deuterium atom per molecule

Which among the following is corect IUPAC name ?

0%
1, 1 - Dimethyl cyclohexan - 3 - ol
0%
4 - Methyl bicyclo [3 . 2 . 0] heptane
0%
Butane - 1, 2 - dione
0%
4 - Ethyl -5 - methyl cyclohexene

The IUPAC name of the following compound is: 2 - bromo - 6 - chlorophenol

0%
True
0%
False

Explanation

Parent molecule is phenol bromine is given preference over chlorine while numbering due to fact that bromine comes first in alphabetical order.

So,numbering will be as

$2-$ bromo

$-6-$ chloro-phenol.

The IUPAC name of the following compound is 2, 4, 6 - tribromophenol.

0%
True
0%
False

Explanation

$-OH$ is given preference over bromine.

$OH$ is a functional group so it will get the lowest number. i.e numbering will start from

$C$ attach to

$-OH$ group.Without bromine groups the structure is phenol and at 2,4, and 6 positions three bromo groups are attached. Hence the name will be 2,4,6-tribromophenol

So, the statement is true.

The conversation of m- nitrophenol to resorcinol involves _________ respectively.

0%
hydrolysis, diasotisation and reduction
0%
diasotisation, reduction and hydrolysis
0%
hydrolysis, reduction and diazotisation
0%
reduction,diazotisation and hydrolysis

Which of the following species show maximum volatility?

0%
$CH_3CH_2OH$
0%
$CH_3-O-CH_3$
0%
$H_2O$
0%
$HF$

Explanation

Due to the lack of any Hydrogen bonding in case of

$CH_3-O-CH_3$ , its boiling point is comparatively low. In other words, it is the most volatile among the given compounds.
Hence, Option B is correct.

What is its IUPAC name?

$CH_3-\underset{\displaystyle CH_3}{\underset{|}{CH}}-CH_2-OH$ .

0%
2-methyl propanol
0%
2-ethyl ethanol
0%
3-methyl propanol
0%
3-ethyl ethanol

Explanation

$\overset{3}{C}H_3-\overset{2}{\underset{CH_3}{\underset{|}{CH}}}-\overset{1\,\,\,\,\,}{CH_2}-OH$

2-Methyl propanol.

Given the major product of the following reaction:

0%
0%
0%
0%
None of these

On boiling with concentrated hydrobromic acid, phenyl ethyl ether will yield:

0%
phenol and ethyl bromide
0%
phenol and ethane
0%
bromobenzene and ethanol
0%
bromobenzene and ethane

Explanation

On boiling with concentrated hydrobromic acid, phenyl ethyl ether will yield phenol and ethyl bromide.

Hence, option

$A$ is correct.

997006_1034532_ans_21b2a2ffa12f4fb0a993d56345e65793.png

What is the functional group in alcohol?

0%
$-OH$
0%
$-CN$
0%
$-NC$
0%
- $NH_2$

Explanation

$-OH$ (Hydroxyl group) is the functional group of alcohol. Because, if we add

$-OH$ to a Methyl group

$(-CH_3)$ , it will be converted to Methyl alcohol

$(CH_3OH)$

The compound A on treatment with Na gives B, and with

${ PCI }_{ 5 }$ gives C. B and C react together to give diethyl ether. A, B and C are in the order.

0%
${ C }_{ 2 }{ H }_{ 5 }{ OH },C_{ 2 }{ H }_{ 5 }ONa,{ C }_{ 2 }{ H }_{ 5 }Cl$
0%
${ C }_{ 2 }{ H }_{ 5 }Cl,{ C }_{ 2 }{ H }_{ 6 },{ C }_{ 2 }{ H }_{ 5 }OH$
0%
${ C }_{ 2 }{ H }_{ 5 }OH,{ C }_{ 2 }{ H }_{ 5 }Cl,{ C }_{ 2 }{ H }_{ 5 }ONa$
0%
${ C }_{ 2 }{ H }_{ 5 }OH,{ C }_{ 2 }{ H }_{ 6 },{ C }_{ 2 }{ H }_{ 5 }Cl$

$3$ -methyl-

$2$ -pentene on reaction with HOCl gives:

0%
$3$ -chloro- $3$ -methyl pentanol- $2$
0%
$2, 3$ -dichloro- $3$ -methyl pentane
0%
$2$ -chloro- $3$ -methyl pentanol- $3$
0%
$2, 3$ dimethyl butanol- $2$

Explanation

The given reaction follows Markownikoff's addition mechanism and add

$OH^-$ and

$Cl^+$ across carbon-carbon double bond.
1171781_1034256_ans_995a9433438544a5a9986d831bf2166b.PNG

In which of the following reactions, the product obtained is tert-butyl methyl ether?

0%
$CH_3OH+HO-CH_2-CH_3\overset{Conc. H_2SO_4}{\rightarrow}$
0%
$H_3C-\overset{CH_3}{\overset{|}{\underset{CH_3}{\underset{|}{C}}}}-Br+CH_3OH\overset{OH^-Na^+}{\rightarrow}$
0%
$CH_3Br+Na^+O^--\overset{CH_3}{\overset{|}{\underset{CH_3}{\underset{|}{C}}}}-CH_3\rightarrow$
0%
$CH_3-O^-Na^++CH_3-\overset{CH_3}{\overset{|}{\underset{CH_3}{\underset{|}{C}}}}-Br\rightarrow$

Explanation

The product can be obtained by Williamson's synthesis and it involves an

$S_N2$ pathway.
Thus we can see that Option D is not possible as it will lead to

$E2$ products.
Therefore, Option C is the correct option.

1051463_1038354_ans_a9564a92c5a74d888bd573295229f7db.jpg

Which of the following is the best reagent to convert cyclohexanol into cyclohexene?

0%
Conc. $HCl$
0%
Conc. $HBr$
0%
Conc. ${ H }_{ 3 }{ PO }_{ 4 }$
0%
Conc. $HCl$ with ${ ZnCl }_{ 2 }$

Explanation

Conc.

${ H }_{ 3 }{ PO }_{ 4 }$ is a good dehydrating agent which converts an alcohal to an alkene while the other three reagents are nucleophiles which convert alcohals to alkyl halides.
979651_1060991_ans_67ccc6a403234994852b77896e942ad5.jpg

979651_1060991_ans_67ccc6a403234994852b77896e942ad5.jpg

Which of the following is not the product of dehydration of the given?

Find out the total number of 1, 2 shifts in this reaction.

0%
2
0%
3
0%
5
0%
6

$Ph - C \equiv C - Ph \xrightarrow{Na/NH_3} A \xrightarrow{HOCl/H^+} B$

$B$ is/are:

$1-$ Bromopentane on boiling with alcoholic potassium hydroxide gives:

0%
Pentan $-1-ol$
0%
Pentan $-2-ol$
0%
pent $-1-ene$
0%
pent $-2-ene$

Major product of the given reaction is:

Explanation

Dehydration of alcohol( Elimination reaction): It is so called because of elimination of

$H_2O$ molecule. Refer to the image.

The elimination of

$H^+$ from other side will form diene which is less stable, so the product formed above is major product.

1004966_1068649_ans_4c315dfb754b4b6a9cae13a2e87b508a.png

Which of the following leads to formation of

${ 1 }^{ 0 }$ alcohol?

0%
${ CH }_{ 3 }-CH={ CH }_{ 2 }\xrightarrow [ { H }^{ + } ]{ { H }_{ 2 }O }$
0%
${ CH }_{ 3 }-CH={ CH }_{ 2 }\xrightarrow [ Hg{ \left( OAc \right) }_{ 2 }/THF ]{ Na{ BH }_{ 4 }/{ OH }^{ \ominus } }$
0%
${ CH }_{ 3 }-CH={ CH }_{ 2 }\xrightarrow [ { B }_{ 2 }{ H }_{ 6 }/THF ]{ { H }_{ 2 }{ O }_{ 2 }/{ OH }^{ \ominus } }$
0%
${ CH }_{ 3 }-C\equiv C-{ CH }_{ 3 }\xrightarrow [ dil.Hg{ SO }_{ 4 } ]{ dil.{ H }_{ 2 }{ SO }_{ 4 } }$

Explanation

Morbenzene rule

$\rightarrow H^+$ goes to carbon having more hydrogen among the double bond ones.
1424151_1067891_ans_72cf56fa1cd940ad97e72f99f5888cc6.png

The IUPAC name of the compound is:

0%
3, 4 - dimethyl - 2 - butene - 4 - ol
0%
1, 2 - dimethyl - 2- butenol
0%
3 - methylpent - 3 - en - 2- ol
0%
2, 3 - dimethyl - 3- Pentenol

Explanation

For naming a compound, the longest carbon chain is considered and the carbon atom near the functional group is given the first number or priority.

Hence,

$-OH$ is at second carbon and a double bond is between third carbon. Also, a methyl group is present at the third carbon.

So, the IUPAC name of the compound will be

$3-methyl pent-3-en-2-ol$ .

Hence, option

$C$ is correct.

Which of the following is the best reagent to convert

$1-$ Methylcyclohexene into

$2-$ methylcyclohexanol?

0%
dil. $H_2SO_4$
0%
$Hg(OAc)_2/NaBH_4, H_2O$
0%
$B_2H_6/H_2O_2, \overset{\ominus}{O}H$
0%
conc. $H_2SO_4$

The compound a on treatment with Na gives B, and with

${ PCI }_{ 5 }$ gives C, B and C react together to give diethyl ether, A, B and C are in the order?

0%
${ C }_{ 2 }{ H }_{ 5 }OH,{ C }_{ 2 }{ H }_{ 6 },{ C }_{ 2 }{ H }_{ 5 }Cl$
0%
${ C }_{ 2 }{ H }_{ 5 }OH,{ C }_{ 2 }{ H }_{ 5 }CI,{ C }_{ 2 }{ H }_{ 5 }ONa$
0%
${ C }_{ 2 }{ H }_{ 5 }OH,{ C }_{ 2 }{ H }_{ 5 }ONa,{ C }_{ 2 }{ H }_{ 5 }Cl$
0%
$C_{ 2 }{ H }_{ 5 }CI,{ C }_{ 2 }{ H }_{ 6 },{ C }_{ 2 }{ H }_{ 5 }OH$

Explanation

$A \xrightarrow{Na} B \xrightarrow{PCls} C$

One of

$B$ &

$C$ must be

$Et- O Na$ & other

$Et - Cl$

$Et\ ONa$ on reaction

$PCl_3$ gives

$Et\ Cl$

$\therefore B = Et \, ONa$

$C = Et - Cl$

Hence A must be

$Et - OH$

1420310_1079381_ans_ce2350ece86841389d8257c273704f8b.png

Which of the following ether is not cleaved by HI even at 525K ?

0%
${ C }_{ 6 }{ H }_{ 5 }-O-{ CH }_{ 3 }$
0%
${ C }_{ 6 }{ H }_{ 5 }-O-{ C }_{ 6 }{ H }_{ 5 }$
0%
${ C }_{ 6 }{ H }_{ 5 }-O-{ C }_{ 3 }{ H }_{ 7 }$
0%

Explanation

Will not cleaned by HI even at

$525k$ temperature.Cyclic ether don't reaction by HI.
1157607_1080160_ans_754424756c704a25b38035d30b1d41ef.PNG

Arrange the following alkanols 1, 2 and 3 in order of their reactivity towards acid catalyzed dehydration.

0%
$1>2>3$
0%
$2>1>3$
0%
$2>3>1$
0%
$3>2>1$

$\underrightarrow { { H }^{ 2 } }$

Identify

$Z$ in the sequence of reaction,

$CH_3CH_2CH = CH_2 \xrightarrow{HBr/H_2O_2} Y \xrightarrow{C_2H_5ON_a} Z$

0%
$(CH_3)_2CH_2 - O - CH_2CH_3$
0%
$CH_3(CH_2)_4 - O - CH_3$
0%
$CH_3CH_2 - CH(CH_3) - O - CH_2CH_3$
0%
$CH_3 - (CH_2)_3 - O - CH_2CH_3$

Propene is allowed to react with HBr in the presence of benzoyl peroxide, and the product is subsequently heated with aqueous KOH. The final product obtained is: