Question

Which of the following is not a characteristic of alcohol ?

• A. They are lighter than water.
• B. Their boiling points rise fairly uniformly with rising molecular weight.
• C. Lower members are insoluble in water and organic solvents but the solubility regularly increases with molecular mass.
• D. Lower members have a pleasant smell and burning taste, higher members are colourless and tasteless.
• E. Higher members have a pleasant smell and burning taste, lower members are colourless and tasteless.

Answer 1

Answer: (C)

Lower members are insoluble in water and organic solvents but the solubility regularly increases with molecular mass.

A. Alcohols are lighter than water because water molecules are closely packed together due to extensive H-bonding, which means that it has more mass in the same volume than either alcohol or oil. In addition, alcohol is made up of carbon and hydrogen atoms while water is made up of oxygen and hydrogen atoms.

B. Their boiling points rise fairly uniformly with rising molecular weight this is because boiling point depends on the intermolecular interactions such as H-bonding which decreases as the chain length decreases.

C. Lower members are soluble in water and organic solvents but the solubility regularly decreases with molecular mass because of ease of H-bonding in smaller alcohol molecules than those having long hydrocarbon chain.

D. Lower members have a pleasant smell and burning taste, higher members are colourless and tasteless.