If I remember correctly from APUSH, the central government had no authority to tax so the taxation was left to state governments.
I believe the answer is: Integrative theory
Integrative theory view that society could never be exist unless each individuals fulfill their own roles. These happen because humans are unique in terms of our talent/capabilities. So in order to crate a well functioning society, different humans had to integrate our different capability to operate it.
As the substance melts the particles have a higher chance of colliding with one another and also move much faster than when the substance is solid. This is because the particles have a higher surface area to move around. Also the arrangements of particles are free.
