Text Book Back Questions and Answers - Chapter 11 - Hydroxy Compounds and Ethers - 12th Chemistry Guide Samacheer Kalvi Solutions

---

You can Download the Text Book Back Questions and Answers - Chapter 11 - Hydroxy Compounds and Ethers - 12th Chemistry Guide Samacheer Kalvi Solutions with expert answers for all chapters. Perfect for Tamil & English Medium students to revise the syllabus and score more marks in board exams. Download and share it with your friends

Share this to Friend on WhatsApp

Hydroxy Compounds and Ethers
Textual Evaluation Solved
Multiple Choice Questions
Question 1.
An alcohol (x) gives blue colour in victormayer's test and $3.7 \mathrm{~g}$ of $\mathrm{X}$ when treated with metallic sodium liberates $560 \mathrm{~mL}$ of hydrogen at $273 \mathrm{~K}$ and $1 \mathrm{~atm}$ pressure what will be the possible structure of $\mathrm{X}$ ?
(a) $\mathrm{CH}_3 \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_2 \mathrm{CH}_3$
(b) $\mathrm{CH}_3-\mathrm{CH}(\mathrm{OH})-\mathrm{CH}_3$
(c) $\mathrm{CH}_3-\mathrm{C}(\mathrm{OH})\left(\mathrm{CH}_3\right)_2$
(d) $\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}(\mathrm{OH})-\mathrm{CH}_2-\mathrm{CH}_3$
Answer:
(a) $\mathrm{CH}_3 \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_2 \mathrm{CH}_3$
Hint:
$2 \mathrm{R}-\mathrm{OH}+\mathrm{Na} \rightarrow 2 \mathrm{RONa}+2 \mathrm{H}_2 \uparrow 2$ moles of alcohol gives 1 mole of $\mathrm{H}_2$ which occupies
$22.4 \mathrm{~L}$ at $273 \mathrm{~K}$ and $1 \mathrm{~atm}$
number of moles of alcohol $=\frac{2 \text { moles of } \mathrm{R}-\mathrm{OH}}{22.4 \mathrm{~L} \text { of } \mathrm{H}_2} \times 560 \mathrm{~mL}=0.05$ moles
number of moles $=\frac{\text { mass }}{\text { molar mass }}$
$=$ molar mass $=\frac{3.7}{0.05}=74 \mathrm{~g} \mathrm{~mol}^{-1}$
General formula for
$\mathrm{R}-\mathrm{OH} \mathrm{C} \mathrm{C}_{2 \mathrm{n}+1}-\mathrm{OH}$
$\mathrm{n}(12)+(2 \mathrm{n}+1)(1)+16+1=74$
$14 \mathrm{n}=74-18$
$14 \mathrm{n}=56$
$\mathrm{n}=\frac{56}{4}=4$
The $2^{\circ}$ alcohol which contains 4 carbon is $\mathrm{CH}_{\mathrm{n}} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_2 \mathrm{CH}_3$
Question 2.
Which of the following compounds on reaction with methyl magnesium bromide will give tertiary alcohol.
(a) benzaldehyde

(b) propanoic acid
(c) methyl propanoate
(d) acetaldehyde
Answer:
(c) methyl propanoate
Hint:

Question 3.

This ' $\mathrm{X}$ ' is

(d) None of these
Answer:

Hint:
hydro boration - Anti markownikoff product
i.e $\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{OH}$
Question 4.
In the reaction sequence, Ethane

Ethan - 1,2 - diol. $\mathrm{A}$ and $\mathrm{X}$ respectively are
(a) Chioroethane and $\mathrm{NaOH}$
(b) ethanol and $\mathrm{H}_2 \mathrm{SO}_4$
(c) 2-chloroethan - - - ol and $\mathrm{NaHCO}_3$
(d) ethanol and $\mathrm{H}_2 \mathrm{O}$
Answer:
(c) 2 - chloroethan - - ol and $\mathrm{NaHCO}_3$
Hint:

Question 5.
Which one of the following is the strongest acid
(a) 2-nitrophenol
(b) 4-chlorophenol
(c) 4-nitrophenol
(d) 3-nitrophenol
Answer:
(c) 4- nitrophenol
Question 6.

$\text { on treatment with Con. } \mathrm{H}_2 \mathrm{SO}_4 \text {, predominately gives }$

Answer:

Hint:

Question 7.
Carbolic acid is
(a) Phenol
(b) Picric acid
(c) benzoic acid
(d) phenylacetic acid
Answer:
(a) Phenol
Question 8.
Which one of the following will react with phenol to give salicyladehyde after hydrolysis
(a) Dichioro methane
(b) trichioroethane
(c) trichloro methane
(d) $\mathrm{CO}_2$
Answer:
(c) trichloro methane (Riemer Tiemann reaction)
Hint:

Question 9.
$
\left(\mathrm{CH}_3\right)_3-\mathrm{C}-\mathrm{CH}(\mathrm{OH}) \mathrm{CH}_3 \stackrel{\text { Conc. } \mathrm{H}_2 \mathrm{SO}_4}{\longrightarrow} \mathrm{X} \text { (major product) }
$
(a) $\left(\mathrm{CH}_3\right)_3 \mathrm{CCH}=\mathrm{CH}_2$
(b) $\left(\mathrm{CH}_3\right)_2 \mathrm{C}=\mathrm{C}\left(\mathrm{CH}_3\right)_2$
(c) $\mathrm{CH}_2=\mathrm{C}\left(\mathrm{CH}_3\right) \mathrm{CH}_2-\mathrm{CH}_2-\mathrm{CH}_3$
(d) $\mathrm{CH}_2=\mathrm{C}\left(\mathrm{CH}_3\right)-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{CH}_3$
Answer:
(b) $\left(\mathrm{CH}_3\right)_2 \mathrm{C}=\mathrm{C}\left(\mathrm{CH}_3\right)_2$
Hint:

Question 10.

The correct IUPAC name of the compound, 

(a) 4 - chloro-2,3-dimethyl pentan-1-ol
(b) 2, 3-dimethyl-4-chloropentan - 1-ol
(c) 2, 3,4-trimethyl-4-chiorobutan - 1-ol
(d) 4-chioro-2,3,4-trimethyl pentan - 1-ol
Answer:
(a) 4-chloro-2,3-dimethyl pentan-1-ol
Question 11.
Assertion: Phenol is more acidic than ethanol
Reason: Phenoxide ion is resonance stabilized
(a) if both assertion and reason are true and reason is the correct explanation of assertion.
(b) if both assertion and reason are true but reason is not the correct explanation of assertion.
(c) assertion is true but reason is false
(d) both assertion and reason are false.
Answer:
if both assertion and reason are true and reason is the correct explanation of assertion.
Question 12.
In the reaction Ethanol

(a) ethane
(b) ethoxyethane
(c) ethylbisuiphite
(d) ethanol
Answer:
(d) ethanol
Hint:

Question 13.
The reaction

can be classified as
(a) dehydration
(b) Williams on alcoholsynthesis
(c) Williamson ether synthesis
(d) dehydrogenation of alcohol
Answer:
(c) Williamson ether synthesis
Hint: Cyclic alcohol $\rightarrow$ sodium cyclic alkoxide $\rightarrow$ williamson ether synthesis
Question 14.
Isoprophylbcnzene on air oxidation in the presence of dilute acid gives
(a) $\mathrm{C}_6 \mathrm{H}_5 \mathrm{COOH}$
(b) $\mathrm{C}_6 \mathrm{H}_5 \mathrm{COCH}_3$
(c) $\mathrm{C}_6 \mathrm{H}_5 \mathrm{COC}_6 \mathrm{H}_5$
(d) $\mathrm{C}_6 \mathrm{H}_5-\mathrm{OH}$
Answer:
(a) $\mathrm{C}_6 \mathrm{H}_5-\mathrm{OH}$ (phenol)
Question 15.
Assertion: Phenol is more reactive than benzene towards electrophilic substitution reaction Reason: In the case of phenol. the intermediate arenium ion is more stabilized by resonance.
(a) if both assertion and reason are true and reason is the correct explanation of assertion.
(b) if both assertion and reason are true but reason is not the correct explanation of assertion.
(c) assertion is true but reason is false
(d) both assertion and reason are false,.
Answer:
(a) if both assertion and reason are true and reason is the correct explanation of assertion.
Question 16.
$\mathrm{HO} \mathrm{CH}_2 \mathrm{CH}_2-\mathrm{OH}$ on heating with periodic acid gives
(a) methanoic acid
(b) Glyoxal
(c) methanol
(d) $\mathrm{CO}_2$
Answer:
(c) methanol

Question 17.
Which of the following compound can be used as artireeze in automobile radiators?
(a) methanol
(b) ethanol
(c) Neopentyl alcohol
(d) ethan -1,2-diol
Answer:
(d) ethan -1, 2-diol
Question 18.

is an example of
(a) Wurtz reaction
(b) cyclic reaction
(c) Williamson reaction
(d) Kolbe reactions
Answer:
(c) Kolbe reactions
Question 19 .
One mole of an organic compound (A) with the formula $\mathrm{C}_3 \mathrm{H}_8 \mathrm{O}$ reacts completely with two moles of $\mathrm{HI}$ to form $\mathrm{X}$ and $\mathrm{Y}$. When $\mathrm{Y}$ is boiled with aqueous alkali it forms $\mathrm{Z} . \mathrm{Z}$ answers the iodoform test. The compound (A) is
(a) propan $-2-\mathrm{ol}$
(b) propan- $1-$ ol
(c) ethoxy ethane
(d) methoxy ehane
Answer:
(d) methoxy ehane
Hint:

Question 20 .
Among the following ethers which one will produce methyl alcohol on treatment with hot $\mathrm{HI}$ ?

Answer:

Question 21.
Williamson synthesis of preparing dimethyl ether is a / an /
(a) $\mathrm{SN}^1$ reactions
(b) $\mathrm{SN}^2$ reaction
(c) electrophilic addition
(d) electrophilic substitution
Answer:
(b) $\mathrm{SN}^2$ reaction
Question 22.
On reacting with neutral ferric chloride, phenol gives
(a) red colour
(b) violet colour
(c) dark green colour
(d) no colouration
Answer:
(b) violet colour
II. Answer the following questions
Question 1.
IdentIfy the product (s) is / are formed when 1 - methoxy propane is heated with excess HI. Name the mechanism involved in the reaction
Answer:
1-methoxy propane is heated with excess HI, yields two products named as Methyl iodide and 1- iodo propane.
Step 1:

Step 2:

Step 3:

Step 4:

Overall reaction:

This reaction ivvolves nucleophilic substitution reaction mechanism. $\left(\mathrm{SN}^1\right)$
Question 2.
Draw the major product formed when 1 - ethoxyprop - 1 - ene is heated with one equivalent of $\mathrm{HI}$

Answer:

This reaction follows $\mathrm{SN}^1$ mechanism because in this reaction the more stable carbocation is formed that is double bonded carbocation. Therefore, the given molecule reacts with $\mathrm{HI}$ to form ethanol and 1 - iodo prop - 1 ene.

Question 3.
Suggest a suitable reagent to prepare secondary alcohol with identical group using Grignard reagent.
Answer:
Acetaldehyde reacts with Grignard reagent to give addition product, which on further undergoes acid hydrolysis to yield secondary alcohol, that is isopropyl alcohol.

Question 4 .
What is the major product obtained when two moles of ethyl magnesium bromide is treated with methyl benzoate
followed by acid hydrolysis
Answer:

Question 5.
Predict the major product, when 2-methyl but-2 - ene is converted into an alcohol in each of the following methods.
1. Acid catalysed hydration
2. Hydroboration
3. Hydroylation using bayers reagent
Answer:
1. Acid catalysed hydration:

2. Hydroboration. 

Hydroxylation using bayers reagent: 

Question 6.
Arrange the following in the increasing order of their boiling point and give a reason for your ordering
1. Butan $-2-$ ol, Butan $-1-$ SI, 2-methylpropan $-2-$ ol

2. Propan-1-ol, propan-1,2,3-triol, propan-1,3-diol, propan-2-ol
Answer:
1. Boiling points increases regularly as the molecular mass increases due to a corresponding increase in their Van der waal's force of attraction. Among isomeric alcohols $2^{\circ}$ - alcohols have lower boiling points than $1^{\circ}$ - alcohols due to a corresponding decreases in the extent
of H-bonding because of steric hindrance. Thus the boiling point of Butan $-2-\mathrm{ol}$ is lower than that of Butan -1 $-\mathrm{ol}$. Overall increasing order of boiling points is, $2-$ methylpropan $-2-\mathrm{ol}<\operatorname{Butan}-2-\mathrm{ol}<\operatorname{Butan}-1-\mathrm{ol}$
2. $2^{\circ}$-alcohols have lower boiling points than $1^{\circ}$ - alcohols due to a corresponding decrease in the extent of $\mathrm{H}-$ bonding because of steric hindrance. Therefore Propan - 1 - ol has higher boiling point than Propan - 2-ol. Hydrogen group increases, boiling point also increases. Overall increasing order of boiling points is, propan $-2-$ ol $<$ Propan $-1-$ ol $<$ propan $-1,3$ - diol $<$ propan $-1,2,3$ - triol

Question 7.
Can we use nucelophiles such as $\mathrm{NH}_3, \mathrm{CH}_3 \mathrm{O}$ for the Nucleophilic substitution of alcohols
Answer:
1. Increasing order of nucelophilicity,
$
\mathrm{NH}_3<-\mathrm{OH}^{\oplus}<\mathrm{CH}_3 \mathrm{O}^{\ominus}
$
2. Higher electron density will increase the nucelophilicity.
3. Negatively charged species are almost always more nucelophiles than neutral species.
4. $\mathrm{RO}^{\ominus}$ has an alkyl group attached, allowing a greater amount of polarizability. This means oxygen's lone pairs will be more readily available to reach in $\mathrm{RO}^{\ominus}$ than in $\mathrm{OH}^{\ominus}$. Hence $\mathrm{CH}_3 \mathrm{O}$ - is the better nucelophile for the nucleophilic substitution of alcohols. $\mathrm{NH}_3$ cannot act as nucelophile for the nucleophilic substitution of alcohols.

Question 8 .
Is it possible to oxidise $\mathrm{t}$ - butyl alcohol using acidified dichromate to form a carbonyic compound.
Answer:
$3^{\circ}-$ alcohols do not undergo oxidation reaction under normal condition, but at elevated temperature, under strong oxidising agent cleavage of $\mathrm{C}-\mathrm{C}$ bond takes place to give a mixture of carboxylic acid.
Yes, it is possible. $\mathrm{t}$ - butyl alcohol is readily oxidsing in acidic solution $\left(\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7 / \mathrm{H}_2 \mathrm{SO}_4\right)$ to a mixture of a ketone and an acid each containing lesser number of carbon atoms than the original alcohol. The oxidation presumably occur via alkenes formed through dehydration of alcohols under acidic conditions.

Question 9.
What happens when 1 - phenyl ethanol is treated with acidified $\mathrm{KMnO}_4$.

Answer:
1 - phenyl ethanol reacts with acidified $\mathrm{KMnO}_4$ to give Acetophenone.

Question 10 .
Write the mechanism of acid catalysed dehydration of ethanol to give ethene.

Answer:
Mechanism of acid catlaysed dehydration of ethanol:
Step1:
Protonation of ethanol.

Step 2:
Elimination of water molecule.

Question 11.
How is phenol prepared form
1. chloro benzene
2. isopropyl benzene
Answer:
1. From Chioro benzene:
According to Dow's process, when Chiorobenzene is hydrolysed with $6-8 \%$ NaOHat 300 bar and $633 \mathrm{~K}$ in a closed vessel, sodium phcnoxidc is formed which on treatment with dilute $\mathrm{HCl}$ gives phenol.

2. For isopropyl benzene:
On passing air to a mixture of cumene (isoprophy benzene) and $5 \%$ aqueous sodium carbonate solution, cumene hydro peroxide is formed by oxidation. It is treated with dilute acid to get phenol and acetone.

Question 12 .
Explain Kolbe's reaction
Kolbe's (or) Kolbe's Schmitt reaction:
In this reaction, phenol is first converted into sodium phenoxide which is more reactive than phenol towards electrophilic substitution reaction with $\mathrm{CO}_2$. Treatment of sodium phenoxide with $\mathrm{CO}_2$ at $400 \mathrm{~K}, 4$-7 bar pressure followed by acid hydrolysis gives salicylic acid.
Answer:

Question 13.
Writes the chemical equation for Williamson synthesis of 2 - ethoxy - 2-methyl pentane starting from ethanol and $2-$ methyl pentan $-2-\mathrm{ol}$
Answer:
Step 1:

Step 2: 

Step 3: 

Williamsons synthesis occurs by $\mathrm{SN}^2-$ mechanism and primary alkyl halides are more reactive in $\mathrm{SN}^2$ reactions. Therefore ethanol is converted into ethyl bromide.
Question 14.
Write the structure of the aldehyde, carboxylic acid and ester that yield $4-$ methylpent $-2-$ en $-1-$ ol.
Answer:
1. Aldehyde yield $4-$ methylpent $-2-3 n-$ ol is

$\text { 2. Acid yield } 4-\text { methylpent }-2-\text { en }-1-o l \text { is }$

$\text { 3. Ester yield } 4-\text { methylpent }-20 \text { en }-1-\mathrm{ol} \text { is }$

$\text { The above shown compounds undergo reduction reaction to yield } 4-\text { methylpent }-2-\text { en }-1-\text { ol. }$

Question 15.
What is meta merism? Give the structure and IUPAC name of metamers of 2 - methoxy propane
Answer:
Metamerism:
It is a special type of isomerism in which molecules with same formula, same functional group, but different only in the nature of the alkyl group attached to oxygen.

Ethoxy ethane and 1-methoxy propane are metamers of 2-methoxy propane.
Question 16.
How are the following conversions effected
1. benzylchlorjde to benzvlalcohol
2. benzvl alcohol to benzoic acid
Answer:
1. Conversion of benzyl chloride into benzyl alcohol:

2. Conversion of benzyl alcohol into benzoic acid:

Question 17.
Complete the following reactions

(i)

(ii)

(iii)

(iV)

Answer:

(i)

(ii)

(iii)

(iv)

Question 18.
O.44g of a monohydric alcohol when added to methyl magnesium iodide in ether liberates at STP $112 \mathrm{~cm}^3$ of methane with PCC the same alcohol form a carbonyl compound that answers silver mirror test. Identify the compound.
Answer:
$0.44 \mathrm{~g}$ of a monohydric alcohol liberates $112 \mathrm{~cm}^3$ of methane.

Mass of monohydric alcohol which gives $22400 \mathrm{~cm} 3$ of methane $=\frac{22400 \times 0.44}{112}=88$
$\mathrm{C}_5 \mathrm{H}_{12} \mathrm{O}$ molecular fórmula has mass number 88 and it shows eight possible isomers. But neopentyl alcohol reacts with PCC to form neopentyl aldehyde, which shows positive silver mirror test. Therefore, compound is. neopentyl alcohol (or) 2,2 - dimethyl propan $-1-$ ol.

Question 19.
Complete the following reactions

(i)

(ii)

Answer:

(i)

Question 20 .
Phenol is distilled with $\mathrm{Zn}$ dust gives (A) followed by friedel - crafts alkylation with propyl chloride to give a compound $\mathrm{B}, \mathrm{B}$ on oxidation gives (C). Identify $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$.

Answer:

Question  21 .

Identify A, B, C, D and write the complete equation.

Answer:

Question 22 .
What will be the product for the following reaction

Answer:

Question 23.
How will you convert acetylen in to n - butyl alcohol.

Answer:

Question 24 .
Predict the product $\mathrm{A}, \mathrm{B}, \mathrm{X}$ and $\mathrm{Y}$ in the following sequence of reaction

Answer:

Question 25.
3,3 - dimethylbutan $-2-$ ol on treatment with conc. $\mathrm{H}_2 \mathrm{SO}_4$ to give tetramethyl ethylene as a major product. Suggest a suitable mechanisms

Answer:

According to Saytzeff's rule the dehydration of 3,3 - dimethylbutan - - - ol gives a mixture of alkenes. But the secondary carbocation formed in this reaction undergoes rearrangement to form a more stable tertiary
carbocation which further, undergoes to 13 - elimination leads more stable product, that is 2,3 - dimethyl but - 2 - ene (more yield). According to Saytzeff's nile, 2, 3-dimethyl pent- 2 - ene is the major product.
Evaluate yourself
Question 1.
Classify the following alcohols as $1^0, 2^0$, and $3^0$ and give their IUPAC Names.

Answer

Question 2.
Write all the possible isomers of an alacohol having the molecular formula $\mathrm{C}_{15} \mathrm{H}_{12} \mathrm{O}$ and their IUPAC names.

Answer:
Eight isomers are possibe for $\mathrm{C}_{15} \mathrm{H}_{12} \mathrm{O}$. They are,

Question 3.
Suggest a suitable carbonyl compound for the preparation of pent - 2 - en - 1 ol using $\mathrm{LiAlH}_4$.
Answer:

Question 4.

Answer:

Question 5 .
How will you prepare the following using Grignard reagent.
1. $\mathrm{t}$ - butyl alcohol
2. allyl alcohol
Answer:

(i)

(ii)

Question 6.
Identify the products in the following reactions. Write their IUPAC names and mention the mechanism involved in the reactions.

(i)

(ii)

(iii)

Answer:

1.

$\text { This reaction involves } \mathrm{E}_1-\text { mechanism. }$

2.

This reaction ivolves $\mathrm{SN}^2$ - mechanims.

3. Step 1:

Step 2:

This reaction involves $\mathrm{SN}^2$ Mechanims.
Question 7.
What is the major product obtained when 2,3 - dimethyl pentan - 3 -ol is heated in the presence of $\mathrm{H}_2 \mathrm{SO}_4$

Answer:

Question 8 .
Which of the following set of reactants will give $1-$ methoxy -4 - nitrobenzene.

Answer:
Step 1:

step 2:

Chemically both sets equally possible. In Set -1 , the $\mathrm{Br}$-atom is activated by electron withdrawing effect of $\mathrm{NO}_2$ group. Therefore nucleophilic attack by $\mathrm{CH}_3 \mathrm{ONa}$ followed by elimination of $\mathrm{NaBr}$ gives the desired ether.
Step 1:

Step 2:

$\text { In set }-2 \text {, nucleophilic attack by } 4 \text { - nitrosodium phenoxide ion on methyl bromide gives the desired ether. }$

Since alkyl halides $\left(\mathrm{CH}_3 \mathrm{Br}\right)$ are more reactive than aryl halides in nucleophilic substitution reactions, therefore set -2 reactants are preferred.
Question 9.
What happens when $\mathrm{m}$ - cresol is treated with acidic solution of sodium dichromate?
Answer:

When $\mathrm{m}$ - cresol is treated with acidic solution of sodium dichromate it gives 4 - hydroxy beazoic acid.
Question 10.
When phenol is treated with propan $-2-\mathrm{ol}$ in the presence of $\mathrm{HF}$, Friedel-Craft reaction takes place. Identify the products.

Answer: 

Question 11 .
Given the IUPAC name for the following ethers and classify them as simple or mixed.
Answer:

Question 12.
 Which of the following reaction will give $1-$ methoxy $-4-$ nitrobenzene.
1. 4 - nitro - $1-$ bromobenzene + sodium methoxide.
2. 4 - nitrosodium phenoxide + bromomethane
Answer:

Chemically both sets equally possible. In Set -1 , the $\mathrm{Br}-$ atom is activated by electron withdrawing effect of $\mathrm{NO}_2$ group. Therefore nucleophilic attack by $\mathrm{CH}_3 \mathrm{ONa}$ followed by elimination of $\mathrm{NaBr}$ gives the desired ether.
Step 1:

Step 2:

$\text { In set }-2 \text {, nucleophilic attack by } 4 \text { - nitrosodium phenoxide ion on methyl bromide gives the desired ether. }$

Since alkyl halides $\left(\mathrm{CH}_3 \mathrm{Br}\right)$ are more reactive than aryl halides in nucleophilic substitution reactions, therefore set -2 reactants are preferred.
Question 13 .
Arrange the following compounds in the increasing order of their acid strength. propan - 1- ol, 2, 4,6trinitroptienol, 3-nitrophenol, 3,5-dinitrophenol, phenol, 4-methyiphenol.
Answer:
Phenols are stronger acids than alcohols because the phenoxide ion left after the removal of proton is stabilized by resonance while the alkoxide ion left after the removal of a proton from alcohol is not stabilized. Thus propan - 1 - ol is much weaker acid than any phenol.

Thus propan- $1-\mathrm{ol}$ is a much weaker acid than any phenol. We know that electron donating groups decrease the acidic character and stronger is the electron donating group, weaker is the phenol.

Compare to propan - $1-\mathrm{ol}, 4$ - methyl phenol is stronger acidic character. But comparing phenol and 4-methyl phenol, phenol is stronger acidic. Since electron withdrawing groups increase the acidic character of phenols and the effect is more pronounced at the para position than at the meta position.

Therefore 4- nitro phenol is a stronger acid than 3 - nitro phenol. Further as the number of electron withdrawing groups increases the acidic strength further increases. Therefore 2, 4,6-trinitro phenol is a stronger acid than 3 , 5 - dintiro phenol. It may be noted here that although the two nitro groups in 3,5 - dinitro phenol are at $\mathrm{m}$ position with respect to $\mathrm{OH}$ group,
their combined effect is however greater than one nitro group at $\mathrm{p}-$ position. Therefore $3,5-$ dinitro phenol is a stronger acid than 4-nitro phenol. Thus, the overall increasing order of acid strength is. Propan $-1-01<4-$ methyl phenol $<$ phenol $<3$ - nitrophenol $<3,5$ - dinitro phenol $<2,4,6$-trinitro phenol.

Question 14 .
1 mole of $\mathrm{HI}$ is allowed to react with $\mathrm{t}$ - butyl methylether. Identify the product and write down the mechanism of the reaction.
Answer:
Step 1:

Step 2:

Step 3:

Overall reaction: