A solution of Na₂SO₄ in water is electrolysed using inert electrodes. The products at cathode and anode are respectively: 

A solution of sodium sulphate in water is electrolysed using inert electrodes. The products at the cathode and anode are H₂​, O₂​ respectively.
Hydrogen ions having lower discharge (or higher reduction) potential than sodium ions will be liberated at the cathode.
2H⁺+2e⁻→H₂​↑
Hydroxide ions having a lower discharge potential than sulphate ions, will be liberated at anode.
4OH⁻→2H_2​O+O_2​+4e⁻