\textbf{232-} Mixing equal volumes of .............. solution with .............. solution forms a buffer solution.
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(1) 0.6 molar $\text{NH}_3$, 0.2 molar $\text{H}_2\text{SO}_4$ \hfill (2) 0.4 molar NaOH, 0.2 molar $\text{HNO}_3$
(3) 0.50 molar $\text{NH}_3$, 0.4 molar $\text{HNO}_3$ \hfill (4) 0.2 molar NaOH, 0.2 molar $\text{H}_2\text{SO}_4$
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