The reason for bleaching action of cl2

Chlorine react with water to form Hypochlorous acid along with Hydrochloric acid,as Hypochlorous acid is very unstable,it release nascent oxygen along with hydrochloric acid ,these nascent oxygen is a powerful beaching agent,and responsible for the bleaching action in CI2

Explanation:

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !

i'm assuming that the correct answer is indeed the first one/ "a"..