i know why the answer should be 1 2 and 6 but for the third one, illogically it makes sense somehow. why is the third one wrong? is it because oxygen should always have -2 charge instead of +2?
You can perceive option 3 in terms of oxidation and reduction here it’s not clearly specified but i think there should be -2 on oxygen and we are adding 2 electrons as we know gain of electron is reduction while the loss is oxidation here on addition of 2 electrons oxygen is getting converted from -2 to 0 which doesn’t makes sense as there should be reduction not oxidation because we are adding electrons.
Hope it helps!