121. Which of the following statements is correct about the acidity of alcohols?
a) Primary alcohols are more acidic than phenols.
b) Phenols are more acidic than alcohols.
c) Tertiary alcohols are more acidic than primary alcohols.
d) Alcohols are non-acidic in nature.
Answer: b) Phenols are more acidic than alcohols.
Explanation: Phenols are more acidic than alcohols due to the resonance stabilization of the phenoxide ion, while alcohols are less acidic.
122. Which of the following alcohols will not give a positive iodoform test?
a) Ethanol
b) Isopropanol
c) Methanol
d) 2-Butanol
Answer: c) Methanol
Explanation: Methanol does not give a positive iodoform test because it does not have a methyl group adjacent to the hydroxyl group, which is required for the reaction.
123. Which of the following processes is used to produce methanol on an industrial scale?
a) Hydration of ethene
b) Hydrogenation of carbon monoxide
c) Fermentation of sugars
d) Dehydration of ethanol
Answer: b) Hydrogenation of carbon monoxide
Explanation: Methanol is produced industrially by the hydrogenation of carbon monoxide (CO) using a catalyst under high temperature and pressure.
124. Which of the following alcohols will be oxidized to a carboxylic acid?
a) 2-Propanol
b) Ethanol
c) 2-Methyl-2-propanol
d) Cyclohexanol
Answer: b) Ethanol
Explanation: Ethanol is a primary alcohol and can be oxidized first to an aldehyde and then to a carboxylic acid.
125. Which reagent is commonly used to oxidize primary alcohols to aldehydes?
a) Potassium permanganate (KMnO₄)
b) Pyridinium chlorochromate (PCC)
c) Sodium borohydride (NaBH₄)
d) Lithium aluminium hydride (LiAlH₄)
Answer: b) Pyridinium chlorochromate (PCC)
Explanation: Pyridinium chlorochromate (PCC) is commonly used to oxidize primary alcohols to aldehydes without further oxidation to carboxylic acids.
126. Which of the following statements is true for the Lucas test for alcohols?
a) The test distinguishes between alcohols based on their boiling points.
b) Tertiary alcohols react immediately, forming a cloudy solution.
c) Primary alcohols react faster than secondary alcohols.
d) The test does not work for tertiary alcohols.
Answer: b) Tertiary alcohols react immediately, forming a cloudy solution.
Explanation: In the Lucas test, tertiary alcohols react almost instantly, forming a cloudy solution due to the formation of an alkyl chloride.
127. Which alcohol is used as an antifreeze in automobile engines?
a) Ethanol
b) Methanol
c) Glycerol
d) Ethylene glycol
Answer: d) Ethylene glycol
Explanation: Ethylene glycol is used as an antifreeze in automobile engines due to its ability to lower the freezing point of water.
128. Which of the following alcohols is used in the preparation of biodiesel?
a) Methanol
b) Ethanol
c) Isopropanol
d) Glycerol
Answer: a) Methanol
Explanation: Methanol is commonly used in the transesterification process to convert triglycerides into biodiesel.
129. What is the main product when 1-propanol is heated with concentrated sulfuric acid?
a) 1-Propene
b) Propanal
c) Propanoic acid
d) 1-Butene
Answer: a) 1-Propene
Explanation: When 1-propanol is heated with concentrated sulfuric acid, it undergoes dehydration, forming 1-propene.
130. Which of the following is an example of a polyhydric alcohol?
a) Methanol
b) Ethanol
c) Glycerol
d) Butanol
Answer: c) Glycerol
Explanation: Glycerol (or glycerine) is a polyhydric alcohol, meaning it contains three hydroxyl groups.
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