a. Suggest a suitable indicator to find the end-points of the reactions between:

i. 0.0500 mol dm^–3 nitric acid and 0.0500 mol dm^–3 aqueous ammonia

ii. 2.00 mol dm^–3 aqueous sodium hydroxide and 1.00 mol dm^–3 sulfuric acid

iii. 0.005 00 mol dm^–3 aqueous potassium hydroxide and 0.005 00 mol dm^–3 butanoic acid

b. Suggest why phenolphthalein would not be a suitable indicator to use to find the end point when 0.0100 mol dm^–3 hydrochloric acid is titrated against 0.0100 mol dm^–3 urea, a weak base.