What is produced at the cathode during the electrolysis of aqueous $Na_2SO_4$?

Which of the following elements is extracted commercially by the electrolysis of an aqueous solution of its compound?

How many moles of electrons are required for the reduction of $1 \ mole$ of $Cr^{3+}$ to $Cr_{(s)}$?

The products obtained at the cathode and anode respectively during the electrolysis of aqueous $K_2SO_4$ solution using platinum electrodes are

Electrolysis of molten anhydrous calcium chloride produces

The number of electrons delivered at the cathode during electrolysis by a current of $1 \ A$ in $60 \ s$ is (charge on electron $= 1.60 \times 10^{-19} \ C$)