Practise O/L exam questions on Acids, Bases and Salts with worked solutions
2021 · Paper II · 6 marks
A student tests four solutions A, B, C and D with universal indicator. The colours obtained are: A — red (pH 2), B — green (pH 7), C — blue (pH 11), D — orange (pH 4).
(i) Identify the acidic, neutral and alkaline solutions.
(ii) Write the word equation for the neutralisation reaction between solutions A and C.
(iii) Name ONE everyday use of an alkali.
Show worked solution
(i) Acidic: A (pH 2) and D (pH 4); Neutral: B (pH 7); Alkaline: C (pH 11).
(ii) Acid + Alkali → Salt + Water (i.e. hydrochloric acid + sodium hydroxide → sodium chloride + water).
(iii) Toothpaste / baking soda for cooking / lime to neutralise acidic soil (any valid example accepted).