(a) What is a buffer solution? Give one example each of an acidic buffer and a basic buffer. (3 marks) (b) Explain, with equations, how a buffer made from ethanoic acid and sodium ethanoate resists a change in pH when (i) a small amount of strong acid is added, and (ii) a small amount of strong base is added. (6 marks) (c) The $pK_a$ of ethanoic acid is 4.76. Calculate the pH of a buffer containing (i) equal concentrations of ethanoic acid and sodium ethanoate, and (ii) 1.0 mol dm$^{-3}$ sodium ethanoate and 0.1 mol dm$^{-3}$ ethanoic acid. (4 marks) (d) State two uses of buffers in living systems or in the laboratory. (2 marks)