Volcano ! *i give ! *
a volcanic occurs when the in a magma becomes so great it is released like a valve. magma is released through the volcano's in an eruption of rocks (bombs) and ash.
a volcanic develops over centuries as flowing from the active volcano to form layers of rock

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 !