Chemistry · Oct / Nov 2022 · Paper 12 · Question 17

The table gives some statements about electrolysis and the reason why each statement is true. Which row shows a correct statement and the correct reason why the statement is true?

1. Astatement: Aqueous copper(II) sulfate and aqueous copper(II) nitrate are suitable electrolytes when used to copper plate objects. reason: Both solutions contain Cu2+(aq) and can transfer copper from the anode to the cathode.
2. Bstatement: During the extraction of aluminium from aluminium oxide the carbon anodes have to be replaced regularly. reason: The anodes gradually dissolve in the molten cryolite.
3. Cstatement: In the electrolysis of concentrated aqueous sodium chloride and of dilute sulfuric acid the same products are formed. reason: H+(aq) is present in both aqueous solutions.
4. Dstatement: When an aqueous mixture of zinc nitrate and copper(II) sulfate is electrolysed, zinc is formed on the cathode. reason: Zinc is more reactive than copper.

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