A student uses a lever and fulcrum to lift a rock off the ground. Which option describes when potential energy is converted into kinetic energy during this process?

a. when the lever is wedged beneath the rock but before it has been lifted

b. when the student presses down on one side of the lever to cause it to move

c. when the rock rests on the ground without the lever

d. when the rock rests above the ground

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 !