A football fullback is running down the field at constant speed until he encounters a defensive back. The dot diagram depicts the motion of the fullback.
Indicate on the dot diagram (by means of an arrow) the approximate location at which the fullback-
defensive back collision occurs.
Which direction (right or left) does the force upon the fullback
act? Left Explain how you know.
What happens to the momentum of the fullback upon colliding
with the defensive back?

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 !

it is the most commonly accepted one

the answer is barium and copper bromide