Answer:
c) The distance between the balls increases.
Explanation:
If you drop the balls at the same time, regardless of their masses they accelerate equally, since they will be in free fall.
However, if you drop one of the balls earlier, then that ball will gain velocity, whereas the second ball has zero initial velocity. At the time the second ball is dropped, both balls have the same acceleration but different initial velocities.
According to the below kinematics equation:

The initial velocity of the first ball will make the difference, and the first ball will travel a greater distance than the second ball. Hence, their distance increases.
A mercury filled balloon would fall faster then water. Mercury is heavier.
Close the switch would be the correct answer
Answer:
The slope of a graph of position vs time