What happens to a helium balloon at a party on a hot day

What happens to a helium balloon at a party on a hot day if the balloon was filled on a cold morning?
    
 a.
The balloon shrinks because the warmer day temperature speeds up the helium atoms and increases the number of atoms that escape through the inner wall of the balloon.
 b.
The balloon expands because the warmer day temperature causes the helium atoms to be less attracted to each other and allows them to occupy more space inside the balloon.
 c.
The balloon expands because the warmer day temperature speeds up the helium atoms and increases the force and frequency of gas collisions on the inner wall of the balloon.
 d.
The balloon shrinks because the warmer day temperature causes the helium atoms to be more attracted to each other and allows them to occupy less space inside the balloon.
 e.
The balloon keeps the same volume because the amount of gas inside the balloon does not change.


What is the correct name for the layer in which weather phenomena occur?
    
 a.
ionosphere
 b.
thermosphere
 c.
mesosphere
 d.
stratosphere
 e.
troposphere



When the external pressure on a balloon is decreased at constant temperature, what happens to the gas inside?
   
 a.
The collisions become more elastic.
 b.
The gas undergoes no changes.
 c.
The volume increases.
 d.
The molecules increase in rate of movement.
 e.
The volume decreases.