Q.A current of 1.608 A is passed through 250 mL of a 0.5M solution of copper sulphate for 50 minutes. Calculate the strength of $\text{Cu}^{2+}$ after electrolysis, assuming volume to be constant and the current efficiency is 100%.

Electrolysis uses electrical energy from an external DC source to drive a non-spontaneous reaction — typically decomposing a stable compound into its elements — inside a device called an electrolytic cell. Electrolysing molten NaCl illustrates the pattern: Na⁺ ions migrate to the cathode and are reduced to Na(l) ($E^{o}=-2.71$ V), while Cl⁻ ions migrate to the anode and are oxidised to Cl2(g) ($E^{o}=-1.36$ V), giving an overall $E^{o}=-4.07$ V — confirming the reaction is non-spontaneous, exactly as expected, so a voltage greater than 4.07 V must be supplied. Oxidation still occurs at the anode and reduction at the cathode as in a galvanic cell, but the electrode SIGNS reverse: the cathode is negative and the anode positive, because the external supply is forcing electrons in rather than the reaction pushing them out. …