An aqueous solution of potassium nitrate (KNO3\text{KNO}_3KNO3) is electrolysed using inert platinum electrodes. The four ions present in this solution are:
K+,NO3−,H+,OH− \text{K}^+, \quad \text{NO}_3^-, \quad \text{H}^+, \quad \text{OH}^- K+,NO3−,H+,OH−Which of the following pairs of ions are attracted to the negative electrode (cathode) during the electrolysis?
NO3−\text{NO}_3^-NO3− and OH−\text{OH}^-OH−
K+\text{K}^+K+ and H+\text{H}^+H+
K+\text{K}^+K+ and NO3−\text{NO}_3^-NO3−
H+\text{H}^+H+ and OH−\text{OH}^-OH−
83 exam-style questions on Edexcel GCSE Chemistry 4.2 Electrolytic processes, covering 4.2.1 Electrolytes and the process of electrolysis, 4.2.2 Products of electrolysis using inert electrodes, 4.2.3 Half equations, oxidation and reduction in electrolysis, and 4.2.4 Electrolysis of copper sulfate and purifying copper. Each one has a worked solution and a mark scheme showing where the marks go.