Question

Which among the following is not a characteristic of alcohols?

• A. Alcohols are polar molecules due to presence of -OH group.
• B. Lower members of alcohols are insoluble in water as well as in organic solvents.
• C. Boiling point of alcohols increases with increase in their molecular mass.
• D. Methanol is toxic liquid.

Answer 1

The Correct Option is B

Let's analyze the options to find out which one is not a characteristic of alcohols.

Option 1: Alcohols are polar molecules due to the presence of -OH group.

This statement is true. Alcohols are indeed polar molecules. The presence of the -OH group (hydroxyl group) creates a partial positive charge on the hydrogen atom and a partial negative charge on the oxygen atom, making the molecule polar. This polarity allows alcohols to dissolve in water and interact with other polar substances.

Option 2: Lower members of alcohols are insoluble in water as well as in organic solvents.

This statement is incorrect. Lower members (such as methanol, ethanol, and propanol) are very soluble in water because of their small size and the ability to form hydrogen bonds with water molecules. Higher alcohols, however, tend to become less soluble in water as the non-polar hydrocarbon tail increases in size. Thus, the lower members are soluble in both water and organic solvents, making this option not a characteristic of alcohols.

Option 3: Boiling point of alcohols increases with an increase in their molecular mass.

This statement is true. As the molecular mass of alcohols increases, the boiling point tends to increase as well. This is because larger alcohol molecules have more electrons and stronger London dispersion forces, which require more energy to break during boiling. Additionally, larger alcohols can form more hydrogen bonds, further increasing the boiling point.

Option 4: Methanol is a toxic liquid.

This statement is true. Methanol (CH₃OH) is indeed toxic. It can cause serious harm if ingested, inhaled, or absorbed through the skin. Methanol is metabolized in the liver to formaldehyde, which is highly toxic and can cause permanent damage to organs or even death.

Conclusion:

The correct answer is Option 2: Lower members of alcohols are insoluble in water as well as in organic solvents. This is not a characteristic of alcohols, as the lower members of alcohols are actually soluble in water, contradicting this statement.