Why are there different theories about the effects of global warming? a. there is no data to support global warming. b. global climate is complex, so changes in global climate are hard to predict. c. increased levels of carbon dioxide are offset by other changes. d. there has been a decrease of extreme weather.
b

i think a, hope it .

explanation:

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 !