On electrolysing `CuSO_4` solution. In presence of Pt the solution becomes colourless why?

If the quantity of electricity required to liberate 2.6267 g of gold from a solution of gold salt is used for the the electrolysis of CuSO_(4) solution in presence of copper anode, then 1.26 g of copper gets dissolved. Find the oxidation number of gold in the gold salt. [Cu=63, Au=197]

During the electrolysis of CuSO_(4) solution in presence of cooper electrodes, the Cu - anode is depleted. Why ?

When aqueous CuSO_(4) solution is elestrolysed in presence of two plantinum electrodes , the solution becomes acidic . Why ?

Reaction at the anode during the electrolysis of aqueous CuSO_(4) solution in presence of Cu electrode is -

When phenolphthalein is added to an aqueous solution of borax, the solution becomes pink in colour. However, when glycerol is added to the solution, it becomes colourless again. Explain.

When Cl_(2) is passed through KI solution, the solution becomes brown in colour. However, when excess of Cl_(2) is used, the solution becomes colourless. Explain.

What will happen during the electrolysis of aqueous solution of CuSO_(4) in the presence of Cu- electrodes -

Aqueous solution of AgNO_(3) is electrolysed in presence of Ag electrodes. As result, 10.8 g of Ag (atomic mass = 108) is deposited at the cathode. If the same amount of electricity is used to carry out the electrolysis of an aqueous solution of CuSO_(4) in presence of Cu electrodes, then -

Can CuSO_(4) solution be stored in a zinc container?