Assertion: Electrolysis of NaCl solution gives Cl2 gas at anode instead of O2.
Reason: Formation of oxygen at anode requires overvoltage.
Answer & explanation
Correct answer: option 1
Formation of O2 has lower value of Eo than formation of Cl2 even than it is not formed because it requires overvoltage.
Overvoltage: When an e- transfers from electrode to solution or vice-versa then certain activation energy (due to transfer from solid to liquid state or vice-versa) is involved, which is termed as overvoltage. It can be as high as 1V for O2.