Which is atom is the most electrophilic? And why?

The oxygen atom in the lactone participates in resonance with carbonyl carbon so, it decreases the electron deficiency character of the carbonyl carbon. Therefore, the keto carbon atom is more electrophilic than the lactone carbon atom.

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 !

b. th3 n4zc4 pl4t3 15 c0nv3rg1ng w1th the s0uth 4m3ric4n pl4t3.