(a) describe the meanings of the terms acid and alkali in terms of the ions they contain or produce inbr aqueous solution and their effects on Universal Indicator paperbr (b) describe how to test hydrogen ion concentration and hence relative acidity using Universal Indicatorbr paper and the pH scalebr (c) describe the characteristic properties of acids as in reactions with metals, bases and carbonatesbr (d) describe qualitatively the difference between strong and weak acids in terms of the extent ofbr ionisationbr (e) describe neutralisation as a reaction between hydrogen ions and hydroxide ions to producebr water, H+ + OH– → H2Obr (f) describe the importance of controlling the pH in soils and how excess acidity can be treated usingbr calcium hydroxidebr (g) describe the characteristic properties of bases in reactions with acids and with ammonium saltsbr (h) classify oxides as acidic, basic or amphoteric, based on metallicnon-metallic character