Unit 7: Alcohols, Phenols and Ethers PART 3

 Unit 7: Alcohols, Phenols and Ethers PART 3

Multiple Choice Questions (MCQs)

Q1. According to the common system, the name of an alcohol is derived from:
(a) the common name of the alkane
(b) the common name of the alkyl group followed by the word "alcohol"
(c) the IUPAC name of the alkane
(d) the common name of the alkyl group followed by the word "hydroxide"

Ans: (b) the common name of the alkyl group followed by the word "alcohol"

Q2. What is the common name of CH₃OH?
(a) Methanol
(b) Methyl alcohol
(c) Methanal
(d) Formic alcohol

Ans: (b) Methyl alcohol

Q3. According to the IUPAC system, the name of an alcohol is derived by substituting the terminal 'e' of the alkane with:
(a) '-al'
(b) '-one'
(c) '-ol'
(d) '-oic acid'

Ans: (c) '-ol'

Q4. In the IUPAC naming of alcohols, the longest carbon chain is numbered starting from the end nearest to the:
(a) alkyl group
(b) hydroxyl group
(c) double bond
(d) aromatic ring

Ans: (b) hydroxyl group

Q5. For naming polyhydric alcohols, the 'e' of the alkane is retained and the ending '-ol' is added along with:
(a) a prefix di, tri, etc.
(b) a suffix di, tri, etc.
(c) a prefix mono, bi, etc.
(d) a suffix -diol only

Ans: (a) a prefix di, tri, etc.

Q6. What is the IUPAC name of HO–CH₂–CH₂–OH?
(a) Ethane-1,2-diol
(b) Ethylene glycol
(c) Ethanol
(d) Ethane-1,1-diol

Ans: (a) Ethane-1,2-diol

Q7. What is the common name of HO–CH₂–CH₂–OH?
(a) Ethyl alcohol
(b) Ethylene glycol
(c) Glycerol
(d) Glycolic acid

Ans: (b) Ethylene glycol

Q8. What is the IUPAC name of glycerol?
(a) Propane-1,2,3-triol
(b) Propane-1,2-diol
(c) Propan-1-ol
(d) Propane-1,1,1-triol

Ans: (a) Propane-1,2,3-triol

Q9. The IUPAC name of isopropyl alcohol is:
(a) Propan-1-ol
(b) Propan-2-ol
(c) 2-Methylpropan-1-ol
(d) 2-Methylpropan-2-ol

Ans: (b) Propan-2-ol

Q10. The common name of CH₃–CH₂–CH₂–CH₂–OH is:
(a) sec-Butyl alcohol
(b) tert-Butyl alcohol
(c) n-Butyl alcohol
(d) Isobutyl alcohol

Ans: (c) n-Butyl alcohol

Q11. The IUPAC name of tert-Butyl alcohol is:
(a) Butan-1-ol
(b) Butan-2-ol
(c) 2-Methylpropan-1-ol
(d) 2-Methylpropan-2-ol

Ans: (d) 2-Methylpropan-2-ol

Q12. The IUPAC name of isobutyl alcohol is:
(a) Butan-1-ol
(b) Butan-2-ol
(c) 2-Methylpropan-1-ol
(d) 2-Methylpropan-2-ol

Ans: (c) 2-Methylpropan-1-ol

Q13. The IUPAC name of sec-Butyl alcohol is:
(a) Butan-1-ol
(b) Butan-2-ol
(c) 2-Methylpropan-1-ol
(d) 2-Methylpropan-2-ol

Ans: (b) Butan-2-ol

Q14. In the IUPAC name "Propan-2-ol", the number '2' indicates the position of the:
(a) alkyl group
(b) hydroxyl group
(c) parent chain
(d) double bond

Ans: (b) hydroxyl group

Q15. The common name of CH₃–CH₂–OH is:
(a) Methyl alcohol
(b) Ethyl alcohol
(c) Propyl alcohol
(d) Butyl alcohol

Ans: (b) Ethyl alcohol

Short Questions with Answers

Q1. How is the common name of an alcohol derived?

Ans: The common name of an alcohol is derived from the common name of the alkyl group followed by the word "alcohol". For example, CH₃OH is methyl alcohol.

Q2. How is the IUPAC name of an alcohol derived?

Ans: According to the IUPAC system, the name of an alcohol is derived from the name of the alkane from which the alcohol is derived, by substituting the terminal 'e' of the alkane with the suffix '-ol'.

Q3. How is the longest carbon chain numbered in the IUPAC naming of alcohols?

Ans: The longest carbon chain (parent chain) is numbered starting at the end nearest to the hydroxyl group.

Q4. How are the positions of substituents and the –OH group indicated in IUPAC nomenclature?

Ans: The positions of the –OH group and other substituents are indicated by using the numbers of carbon atoms to which they are attached.

Q5. How are polyhydric alcohols named according to the IUPAC system?

Ans: For naming polyhydric alcohols, the 'e' of the alkane is retained and the ending '-ol' is added. The number of –OH groups is indicated by adding the multiplicative prefix di, tri, etc. before '-ol'. The positions of –OH groups are indicated by appropriate locants.

Q6. Give the common and IUPAC names of CH₃–CH₂–CH₂–OH.

Ans:

  • Common name: n-Propyl alcohol

  • IUPAC name: Propan-1-ol

Q7. Give the common and IUPAC names of CH₃–CH(OH)–CH₃.

Ans:

  • Common name: Isopropyl alcohol

  • IUPAC name: Propan-2-ol

Q8. Give the common and IUPAC names of (CH₃)₃C–OH.

Ans:

  • Common name: tert-Butyl alcohol

  • IUPAC name: 2-Methylpropan-2-ol

Q9. Give the common and IUPAC names of HO–CH₂–CH₂–OH.

Ans:

  • Common name: Ethylene glycol

  • IUPAC name: Ethane-1,2-diol

Q10. Give the common and IUPAC names of glycerol.

Ans:

  • Common name: Glycerol

  • IUPAC name: Propane-1,2,3-triol

Q11. Write the IUPAC name of the following compound:
CH₃–CH(CH₃)–CH₂–OH

Ans: 2-Methylpropan-1-ol

Q12. Write the IUPAC name of the following compound:
CH₃–CH₂–CH(OH)–CH₃

Ans: Butan-2-ol

Q13. Write the structural formula and IUPAC name of n-Butyl alcohol.

Ans:

  • Structural formula: CH₃–CH₂–CH₂–CH₂–OH

  • IUPAC name: Butan-1-ol

Q14. Write the structural formula and IUPAC name of Isobutyl alcohol.

Ans:

  • Structural formula: (CH₃)₂CH–CH₂–OH

  • IUPAC name: 2-Methylpropan-1-ol

Q15. Why is the 'e' of alkane retained in the naming of polyhydric alcohols?

Ans: The 'e' of alkane is retained in polyhydric alcohols because the ending '-ol' is added along with a multiplicative prefix (di, tri, etc.). For example, ethane-1,2-diol (not ethan-1,2-diol). This helps in clear pronunciation and distinction.

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