How long does it take our solar system to complete one orbit around the Milky Way Galaxy?
A) 100 million years
B) 1 million years
C) 230 thousand years
D) 10 thousand years
E) 230 million years
Question 2
What are the circumstances under which convection can occur in a substance?
A) when the substance is subjected to a strong magnetic field
B) when the substance is strongly cooled from underneath
C) when dense material is being added to the substance
D) when the substance is strongly shaken or disturbed by a strong wind
E) when the substance is strongly heated from underneath