Unit 7: Alcohols, Phenols and Ethers PART 1

 

Unit 7: Alcohols, Phenols and Ethers PART 1

Multiple Choice Questions (MCQs)

Q1. Alcohols and phenols are formed when a hydrogen atom in a hydrocarbon is replaced by:

(a) –CHO group
(b) –OH group
(c) –O– group
(d) –COOH group

Ans: (b) –OH group

Q2. In an alcohol, the –OH group is directly attached to the carbon atom of:

(a) an aromatic system
(b) an aliphatic system
(c) a heterocyclic ring
(d) a benzene ring

Ans: (b) an aliphatic system

Q3. In a phenol, the –OH group is directly attached to the carbon atom of:

(a) an aliphatic chain
(b) an aromatic system
(c) an alkane
(d) an ether

Ans: (b) an aromatic system

Q4. The ordinary spirit used for polishing wooden furniture is chiefly:

(a) methanol
(b) phenol
(c) ethanol
(d) dimethyl ether

Ans: (c) ethanol

Q5. Which of the following is the formula of dimethyl ether?

(a) CH₃OH
(b) C₆H₅OH
(c) CH₃OCH₃
(d) CH₃CH₂OH

Ans: (c) CH₃OCH₃

Q6. Ethers are formed by substituting the hydrogen atom of the hydroxyl group of an alcohol or phenol by:

(a) an alkyl or aryl group
(b) a hydroxyl group
(c) a carboxyl group
(d) an amino group

Ans: (a) an alkyl or aryl group

Q7. Which class of compounds is used in the formation of detergents?

(a) Phenols
(b) Ethers
(c) Alcohols
(d) Aldehydes

Ans: (c) Alcohols

Q8. Which class of compounds is used in the formation of antiseptics?

(a) Alcohols
(b) Phenols
(c) Ethers
(d) Ketones

Ans: (b) Phenols

Q9. Which class of compounds is used in the formation of fragrances?

(a) Alcohols
(b) Phenols
(c) Ethers
(d) Carboxylic acids

Ans: (c) Ethers

Q10. The general formula of an aryloxy group is:

(a) R–O
(b) Ar–O
(c) R–OH
(d) Ar–OH

Ans: (b) Ar–O

Q11. Which of the following contains one or more hydroxyl groups directly attached to carbon atoms of an aromatic system?

(a) Ethanol
(b) Methanol
(c) Phenol
(d) Dimethyl ether

Ans: (c) Phenol

Q12. Paper, cotton, and sugar are all made up of compounds containing:

(a) –CHO groups
(b) –OH groups
(c) –O– groups
(d) –COOH groups

Ans: (b) –OH groups

Short Questions with Answers

Q1. What are alcohols?

Ans: Alcohols are compounds containing one or more hydroxyl (–OH) groups directly attached to carbon atom(s) of an aliphatic system. Example: CH₃OH (methanol).

Q2. What are phenols?

Ans: Phenols are compounds containing one or more hydroxyl (–OH) groups directly attached to carbon atom(s) of an aromatic system. Example: C₆H₅OH (phenol).

Q3. How are ethers formed?

Ans: Ethers are formed by substituting the hydrogen atom of the hydroxyl group of an alcohol or phenol by an alkyl or aryl group. They can also be formed by substituting a hydrogen atom in a hydrocarbon by an alkoxy or aryloxy group (R–O/Ar–O).

Q4. Give the chemical formula and common name of the compound used as ordinary spirit for polishing wooden furniture.

Ans: The compound is ethanol (C₂H₅OH).

Q5. Name three everyday items that are made up of compounds containing –OH groups.

Ans: Sugar, cotton, and paper.

Q6. What is the general formula for an alkoxy group?

Ans: R–O (where R is an alkyl group).

Q7. What is the general formula for an aryloxy group?

Ans: Ar–O (where Ar is an aryl group).

Q8. Give one example each of an alcohol, a phenol, and an ether.

Ans:

  • Alcohol: CH₃OH (Methanol)

  • Phenol: C₆H₅OH (Phenol)

  • Ether: CH₃OCH₃ (Dimethyl ether)

Q9. What are the applications of alcohols, phenols, and ethers in industry?

Ans:

  • Alcohols → used in the formation of detergents

  • Phenols → used in the formation of antiseptics

  • Ethers → used in the formation of fragrances

Q10. How can ethers be visualised in terms of alcohols and phenols?

Ans: Ethers can be visualised as compounds formed by substituting the hydrogen atom of the hydroxyl group of an alcohol or phenol by an alkyl or aryl group.

Q11. Name the compound that is chiefly used as ordinary spirit for polishing wooden furniture.

Ans: Ethanol.

Q12. What is the difference between an alcohol and a phenol in terms of the carbon atom to which the –OH group is attached?

Ans: In alcohols, the –OH group is attached to a carbon atom of an aliphatic system, while in phenols, the –OH group is attached to a carbon atom of an aromatic system.

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