Copper$\left(\mathrm{II}\right)$ ions are blue. When copper$\left(\mathrm{II}\right)$ sulphate solution is electrolysed, the blue solution keeps its colour when copper electrodes are used. Explain the observation.  

Draw a circuit to show how you would test whether mercury conducts. 

Naphthalene is a molecular substance. Do you think it will conduct electricity when molten? Explain. 

What does the electrolysis of this molten compound give? 

Sodium chloride, $\mathrm{NaCl}$.

If you want to purify a metal by electrolysis, will you make it the anode or the cathode? Why? 

Steel cutlery is often electroplated with nickel. Why?