What is the primary reason to have three branches of government?

Ineed to have answers for numbers 2-4 reply to this question

The line dividing regions 4 & 5 on this map is known as the "fall line." which of these represents an important factor of the fall line in georgia history? a) it was the first boundary of the georgia after it became a state. b) it was an important source of power due to a change in elevation. c) it was once home to major cities that have since become abandoned. d) it was a dividing line between the united states and native american territories.

Ascientist performs an experiment where she measures the mass of a piece of metal, pours acid onto the metal, washes the metal, and then re-measures the mass of the metal. the scientist repeats the experiment several times, each time increasing the amount of acid used. the dependent variable in the experiment is the: initial mass of the metal final mass of the metal amount of acid used washing the metal