With easy science!
james took two pea plants, placing one in a dark closet and the other on a sunny window sill. both are located in air-conditioned rooms. he then measured the growth of the pea plants after a week. the growth of pea plants in this experiment is a(n)

a)constant

b)dependent variable

c)independent variable

d)control

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 !