Alcohols Phenols and Ethers Test

Result

Alcohols Phenols and Ethers Test - 39

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Weekly Quiz Competition

Question 1
1 / -0

What is the $$IUPAC$$ name of the following compound?

$$CH_{3} - CH_{2} - CH_{2} - OH$$

A
Propan-1-ol

B
Propan-2-ol

C
Propane-1-ol

D
Ethane-2-ol

Solution

In this compound, the number of carbon atoms is 3. So, the parent alkane is propane.

The functional group present is $$-OH$$ i.e alcohol. $$-OH$$ is present at the first carbon atom

Thus the IUPAC name is Propan - 1 - ol.
Question 2
1 / -0

In which of the following reactions of alcohol there is no cleavage of C-O bond ?

A
Dehydration reaction of alcohol

B
Oxidation reaction of alcohol

C
Reduction reaction of alcohol

D
Reaction of alcohol with phosphorus tribromide

Solution

(a) Dehydration of alcohol
It involves cleavage of C-O bond.

(b) Oxidation of alcohol $$3^o$$ alcohols generally do not undergo oxidation however in the presence of $$KMnO_4$$, cleavage of C-C bond takes place to give two acids in which C-O bond remains uncleaved.

(c) Reduction
$$CH_3CH_2OH \overset{LiAlH_4}{\rightarrow} CH_3CH_3$$
It involves cleavage of C-OH bond.

(d) Reaction with phosphorus tribromide
$$CH_3CH_2OH \overset{PBr_3}{\rightarrow} CH_3CH_2Br$$
It also involves cleavage of C-OH bond.

Thus, oxidation reactions of alcohol do not involve cleavage of C-O bond among the given reactions.
Question 3
1 / -0

Which of the following statement is not correct ?

A
Phenol is neutralised by sodium carbonate

B
Phenol is used to prepare analgesic drugs

C
Solubility of phenol in water is more than that of chlorobenzene

D
Boiling point of o-nitrophenol is lower than that of p-nitrophenol

Solution

Phenol does not react with $$Na_2\, CO_3$$ because it is weaker acid than carboxylic acid and thereby do not have the strength to substitute or give away its H+ ions to that of weak bases like sodium carbonate.

Phenol is used for the preparation of aspirin which is used as an analgesic as well as antipyretic drugs.

Phenol is more soluble in water than chlorobenzene due to formation of H-bond with water molecules.

o-nitrophenol form intramolecular $$H-$$bonding while p-nitrophenol form intermolecular $$H-$$bonding. Due to this, nature o-nitrophenol has a lower boiling point than p-nitrophenol.
Question 4
1 / -0

What is the formula of tertiary butyl acohol?

A
$$CH_{3} - CH(CH_{3}) - CH_{2} - OH$$

B
$$CH_{3} - (CH_{2})_{2}OH$$

C
$$CH_{3} - CH(OH) - CH_{2} - CH_{3}$$

D
$$(CH_{3})_{3} C - OH$$

Solution

Is the formula of tertiary butyl alcohol as in it $$-OH$$ group is attached to tertiary carbon.
Question 5
1 / -0

Which of the following represents monohydric alcohol?

A
$$C_nH_{2n}OH$$

B
$$C_nH_{2n+1}OH$$

C
$$C_nH_{n}O$$

D
$$C_nH_{n}OH$$
Question 6
1 / -0

Which of the following is most soluble in water ?

A
n- butyl alcohol

B
Iso-butyl alcohol

C
Tertiary butyl alcohol

D
None of the above

Solution

Amongst isomeric alcohols, the solubility increases with branching. This is due to the reason that as the branching increases, the surface area of the non-polar hydrocarbon and the solubility increases. So, the sequence of solubility of alcohols are
Tertiary alcohol > secondary alcohol > primary alcohol
Question 7
1 / -0

Dehydration of alcohol is an example of which type of reaction ?

A
Substitution reaction

B
Elimination reaction

C
Rearrangement reaction

D
Addition reaction

Solution

Dehydration of alcohol is an example $$\beta$$-elimination. It involves the lose of two atoms/groups from adjacent carbon atoms.
$$\underset{ethanol}{\overset{\beta }{CH_3}\overset{\alpha }{CH_2}OH} \overset{alc.KOH}{\rightarrow}\underset{ethene }{CH_2 = CH_2} $$
Question 8
1 / -0

Consider the given reaction:
$$\displaystyle CH_3-CH=CH-CH_2-OH \overset{HBr}{\underset{S_N 1}{ \longrightarrow}} [P]$$

In the given reaction the product $$[P]$$ is:

A
$$CH_3-CH=CH-CH_2-Br$$

B
$$CH_3 - \!\!\overset{\,\,\,Br}{\overset{|}{C}}\!\!H - CH = CH_2$$

C
$$CH_2=CH-CH=CH_2$$

D
$$CH_3 - \overset{\,\,\,Br}{\overset{|}{C}}\!\!H - CH_2 - CH_2 - OH$$

Solution

As the dehydration takes place through $$SN^1$$ mechanism so the carbocation intermediate forms.

More stable carbocation gives major product.

The correct answer is $$B$$.
Question 9
1 / -0

The order of reactivity of the following alcohols towards conc. $$HCl$$ is:

A
$$I> II> III> IV$$

B
$$I> III> II> IV$$

C
$$IV> III> II> I$$

D
$$IV> III> I> II$$

Solution

Here we have to check for the stability of carbocation to find the rate of reaction. Higher the stability more is the reactivity
I) will form least stable due to presence of electron withdrawing-F atom

II) will form more stable carbocation then (I) since electron withdrawing-F atom is further away

III) will form more stable than I and II due to presence of two electron donating methyl group

IV) most stable in this case due to resonance (benzyl carbocatio )

So, C option is correct
Question 10
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What is the hybridisation of carbon and oxygen in electronic structure of ether?

A
$$sp^{3}$$ and $$sp^{2}$$

B
$$sp^{3}$$ and $$sp^{3}$$

C
$$sp$$ and $$sp$$

D
$$sp^{2}$$ and $$sp^{2}$$

Solution

$$sp^{3}$$ (4-bond pairs) and $$sp^{3}$$(2-bond pairs and 2-lone pairs) hybridisations of carbon and oxygen in the electronic structure of an ether.