Answer to question 3a) 3b) to plate tectonics

 Answers to questions 3a).3b)....Asked to plate tectonics in my yesterday's post

Pangea Supercontinent and new hypothesis...as Answer

There was only one (first and last) Supercontinent ie pengea. 

The Pengea was formed due to cooling effect over the years

The land mass of Pengea was arranged in such a way that almost half of the land mass was above and below Equator. That is why it did not move prior to it's breaking up

The Pengea broke due to violent quakes and Volcanic eruptions 

Once it was broken in pieces the pieces of land mass started moving to poles

 The plates whose 50%+ land mass was above equator started moving to North pole.north East

  Whereas the plates whose 50%+ land mass was below Equator started moving to South pole

 All land mass will ultimately go to both poles.That is why we have less land mass at Equator and more land mass at both poles.

 The plates which have crossed equator will never return to equator 

There will never be another super continent Now.

The plates move due to Earth rotation and coriolis effect

 The plates near Equator moves faster.

Two plates in One hemisphere can not collide due to opposite motion infact they move in same direction one faster and second slower and hence collide.