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At low pressures, gas viscosity increases as temperature increases, which is mainly due to increase in the intermolecular collision that is caused by an increase in molecular friction. However, at high pressures, gas viscosity decreases as temperature increases. So at low pressures gas is free to move and the distance between molecules is high but in high pressures it's vice versa. So in the first case intermolecular collision creates friction and that's why it hinders the mobility of the gas. But the same collision in the second case can make molecules to move faster because the molecules are packed and it leads to increase in kinetic energy. Is my understanding relevant to this statement? Or is there another reason for changing viscosity in terms of T and P?

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Your understanding is partially relevant to the statement, but it needs some clarification. The statement is about the effect of pressure on the mobility of gas molecules, not the effect of intermolecular collisions. Intermolecular collisions are a factor that affects the mobility of gas molecules, but they are not the only factor. The statement also mentions kinetic energy, which is related to the speed and direction of gas molecules.

At low pressures, gas molecules are free to move around and collide with each other frequently. This means that they have a high kinetic energy and a high probability of changing their direction and speed with each collision. This also means that they have a low mean free path, which is the average distance that a molecule travels between collisions. A low mean free path means that gas molecules can diffuse quickly through a space.

At high pressures, gas molecules are forced to move closer together (making it simpler for them to pass one another)and collide with each other less frequently. This means that they have a low kinetic energy and a low probability of changing their direction and speed with each collision. This also means that they have a high mean free path, which is the average distance that a molecule travels between collisions. A high mean free path means that gas molecules can diffuse slowly through a space.

Therefore, your understanding is correct in saying that intermolecular collisions create friction and hinder the mobility of gas at low pressures, but it is incorrect in saying that they make molecules move faster at high pressures. In fact, it is the opposite: at high pressures, intermolecular collisions reduce friction and increase the mobility of gas by making molecules move faster.

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