Question

Assertion (A) : Ethanoic acid is also known as glacial acetic acid.

Reason (R) : The melting point of pure ethanoic acid is 290 K and hence it often freezes during winters in cold climates.

• A. Both (A) and (R) are true and (R) is correct explanation of the assertion.
• B. Both (A) and (R) are true but (R) is not the correct explanation of the assertion.
• C. (A) is true but (R) is false
• D. (A) is false but (R) is true.

Answer 1

The correct option is A

Both (A) and (R) are true and (R) is correct explanation of the assertion.

Explanation for Correct Option:

Assertion:-

• Ethanoic acid has a chemical formula of ${\mathrm{CH}}_3\mathrm{COOH}$.
• Pure ethanoic acid is called glacial acid.
• This is because acetic acid on reaching its melting point forms a glacier and thus glacial acetic acid.
• Thus assertion is true.

Explanation for reason:-

• The melting point of pure ethanoic acid is 290K$(17°\mathrm{C})$.
• Pure ethanoic acid freezes below room temperature.
• This freezing point is much greater than that of ice.
• Due to this in the winter season it freezes and forms a glacier, when a liquid is associated with ice-like crystals, it is also known to be in its glacial form.
• Therefore, ethanoic acid is also called glacial acetic acid.
• Thus reason is also true and is the correct explanation for the assertion.

Therefore, option (A) Both (A) and (R) are true and (R) is correct explanation of the assertion is the correct answer