A box of gas contains a mixture of two different gases, shown in the figure as blue molecules and red molecules. The temperature and pressure in the box are measured at STP (T = 300 K and p = 1 atmosphere). The blue molecules have 4 times the mass of the red molecules, but there are equal numbers of each kind in the box. The simulation has been running long enough at this time so that the all the measurements have stabilized. (Gravity is turned off in the simulation.) 

1. Which molecules contribute more to the pressure measured by a meter in the wall of the box?
 The blue molecules
 The red molecules
 They contribute equally
 You cannot tell from the information given
2. Which molecules are moving faster?
 On average, the blue molecules are moving twice as fast as the red
 On average, the red molecules are moving twice as fast as the blue
 On average, the blue molecules are moving faster than the red but not twice as fast
 On average, the red molecules are moving faster than the blue but not twice as fast
 You can’t tell from the information given.
An additional amount of red molecules are introduced until the box contains 4 times as many of the red molecules as there are of the blue as shown in the figure at the right.


3. Now how do the average speeds of the molecules compare?
 The red and blue average speeds are the same.
 The average speed of the red molecules is twice as big as that of the blue.
 The average speed of the red molecules is four times as big as that of the blue.
 The average speed of the red molecules is half as big as that of the blue.
 The average speed of the red molecules is one quarter as big as that of the blue.
 You can’t tell from the information given.
4. How do the temperatures of the molecules compare?
 The red and blue temperatures are the same.
 The temperature of the red molecules is twice as high as that of the blue.
 The temperature of the red molecules is four times as high as that of the blue.
 The temperature of the red molecules is half as high as that of the blue.
 The temperature of the red molecules is one quarter as high as that of the blue.
 You can’t tell from the information given.
5. On the average, how do the contributions of the molecules to the force felt on the left wall compare?
 The red and blue exert the same forces.
 The force exerted by the red molecules is twice that of the blue.
 The force exerted by the red molecules is four times that of the blue.
 The force exerted by the red molecules is half that of the blue.
 The force exerted by the red molecules is one quarter that of the blue.
 You can’t tell from the information given.
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