Question

A gas deviates from ideal behavior at a high pressure because its molecules:
A. attract one another
B. show the tyndall effect
C. have kinetic energy
D. are bound by covalent bonds

Answer 1

A gas deviates from its ideal behavior and becomes real because it cannot obey the assumptions of kinetic theory of gases. The major two lacuna of kinetic theory of gases are that the molecules do not have any force of attraction between them and the molecules have a negligible volume as compared to that of the whole container.

Complete step by step answer:
According to the kinetic theory of gases, the assumptions that were deduced are:
(i) The gas consists of very small particles that are known as molecules. This smallness of their size is
such that the total volume of the individual gas molecules added up is negligible compared to the
volume of the smallest open ball containing all the molecules. This is equivalent to stating that the
the average distance separating the gas particles is large compared to their size.
(ii) The molecules are so large that they can be treated under classical mechanics.
(iii) The rapidly moving particles constantly collide among themselves and with the walls of the
container. All the collisions between the molecules are perfectly elastic.
(iv) Except during collisions, the interactions among molecules are negligible and there is no attractive
force present in between them which was later proved wrong and Van der Waal provided some
corrections also based on it.
(v) The average kinetic energy of the gas particles is a function of the absolute temperature of
the system.
(vi)The elapsed time of a collision between a molecule and the containers's wall is negligible when
compared to the time between successive collisions.
(vii) Because they have mass, the molecules will have acceleration due to gravity.
Thus, based on these assumptions we can see that a gas deviates from ideal behavior at a high pressure
because its molecules attract one another with some cohesive forces that exist between them.
The correct option is A. attract one another.

Note:
The causes of deviations from ideal behaviour may be due to the following two assumptions of
kinetic theory of gases.
(i) The volume occupied by gas molecules is negligibly small as compared to the volume occupied by
the gas.
(ii) The forces of attraction between gas molecules are negligible.