Question

Assertion: Buffer system of carbonic acid and sodium bicarbonate is used for the precipitation of hydroxides of third group elements.

Reason: It maintains the pH to a constant value, about 7.4.

• A. Assertion is correct, reason is correct; reason is a correct explanation for assertion.
• B. Assertion is correct, reason is correct; reason is not a correct explanation for assertion
• C. Assertion is correct, reason is incorrect
• D. Assertion is incorrect, reason is correct.

Answer 1

Answer: (D)

Assertion is incorrect, reason is correct.

Answer 2

The assertion claims that a carbonic acid/sodium bicarbonate buffer is used for precipitating third group hydroxides. This is false; an ammonium chloride/ammonium hydroxide buffer is used for this purpose, maintaining a pH of 8-9. The reason states that the carbonic acid/sodium bicarbonate buffer maintains pH around 7.4. This is a correct statement, as this buffer system is crucial for maintaining blood pH at 7.4. Thus, the assertion is incorrect, and the reason is correct.