Question

Which of the following is a basic buffer?

• A. \( \mathrm{NaOH + CH_3COONa} \)
• B. \( \mathrm{NaOH + Na_2SO_4} \)
• C. \( \mathrm{K_2SO_4 + H_2SO_4} \)
• D. \( \mathrm{NH_4OH + NH_4Cl} \)

Hint:

Remember:
Weak base + its salt (with strong acid) → basic buffer
Weak acid + its salt (with strong base) → acidic buffer

Answer 1

The Correct Option is D

Concept: A basic buffer is a solution that resists change in pH and is formed by: \[ \text{Weak base} + \text{Salt of the same base with a strong acid} \]
Step 1: Analyze each option.
\( \mathrm{NaOH + CH_3COONa} \): Strong base + salt → not a buffer
\( \mathrm{NaOH + Na_2SO_4} \): Strong base + neutral salt → not a buffer
\( \mathrm{K_2SO_4 + H_2SO_4} \): Strong acid + salt → acidic mixture
Step 2: Examine option (D). \[ \mathrm{NH_4OH} \; (\text{weak base}) + \mathrm{NH_4Cl} \; (\text{salt of weak base with strong acid}) \] This combination satisfies the condition for a basic buffer. \[ \boxed{\mathrm{NH_4OH + NH_4Cl \; \text{is a basic buffer}}} \]