Jane placed two bar magnets on her desk next to each other with like poles facing. she then sprinkled some iron filings around the magnets. which of the following images best shows how the iron filings arranged themselves?

Top Right image

Explanation:

Like poles of two magnets repel each other. Conventionally the magnetic lines of force are always run  from north to South pole of magnet. In this case the lines of force are Head-to-Head thus repelling each other and forming the Top Right Image.

asthenosphere and convection

1/0.14nm = 10^10/1.4 a lot