Question

David has two containers of two different gases at the same temperature and pressure. David could assume all of following EXCEPT _________.
A. when the temperature is increased, the volume of both containers will increase
B. when the pressure is increased, the volume of both containers will decrease
C. both containers contain the same number of gas particles
D. when the pressure is decreased, the temperature of both containers will increase

Answer 1

Answer:

• David could not assume that:

       when the pressure is decreased, the temperature of both containers will increase (option D).

Explanation:

Since this question has only one answer, you must assume that both containers are identical, i.e. have the same volume.

Using the ideal gas equation pV = nRT you can conclude that pressure and temperature are directly related, i.e. if the pressure is decreased, the temperature will decrease proportionally, which is opposite to the assumption that when the pressure is decreased, the temperature of both containers will increase.

On the other hand, from the same equation, you can tell the relationship between the other variables and conclude that the other choices are valid assumptions:

A. when the temperature is increased, the volume of both containers will increase:

Correct: pV = nRT shows that volume and temperature are directly related: when T increase, V increase)

B. when the pressure is increased, the volume of both containers will decrease

Correct: pV = nRT shows that p and V and inversely related, so when p is incrased, V will decrease.

C. both containers contain the same number of gas particles

Correct, only if the two containers are identical: since the two containers of the two different gases are at the same temperature and pressure, the equation pV = nRT, shows that if the volumes are equal the number of particles are the same.