Which of the following mixtures, in an aqueous solution, will produce a buffer solution?
I. 50 cm3 of 0.1 mol dm–3 CH3COONa and 50 cm3 of 0.1 mol dm–3 CH3COOH
II. 50 cm3 of 0.1 mol dm–3 NH3 and 50 cm3 of 0.1 mol dm–3 NH4Cl
III. 50 cm3 of 0.1 mol dm–3 NaOH and 50 cm3 of 0.2 mol dm–3 CH3COOH
Why Is (I) considered as a buffer?