PLEASE PLEASE HELP ME... i begg you

the answer to the first one is B and the second one is that the volume is a control, the heart rates are dependent, the how music played is controlled, how the heart rates are measured is controlled, the music played is independent

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 !

answer: they produce more slow than unicellular organisms.