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Directions: The following question are based on the passage. Read each statement and shade the appropriate answer in the space provided for it on the answer sheet.

If the temperature of a gas is decreased sufficiently a stage will be reached when the speed of movement of the molecules is so reduced that become close enough to exert attractive forces on each other. These forces differ from the forces that hold the atoms together in a molecule, but they are also electrical intact they result from the attraction between the positively charged nucleus of one atom and the negatively charged orbital electrons of atom in neighboring molecules such forces are called molecular forces (or van der waals' forces, after the discoverer).

At that point in the process of reducing the temperature of a gas when the attractive forces between the molecules are sufficient to market the gas is said to have become a liquid. In contrast to solids however, the molecules of a liquid are still able to slide over one another, so that the bulk is able to adopt the shape of its container.

Some of the more rapid molecules at the surface of a liquid are able to overcome the molecular forces of their neighboring molecules and escape from of the liquid into the gas above it: this process is called evaporation. As it is the fastest moving molecules that escape, that is the molecules with the greatest energy, the average energy of the remaining molecules will be reduced, and hence the effect of evaporation is to cause a reduction in the temperature of the liquid.

As a result of the continual escape of molecules from the surface of a liquid, the gas above it will contain a certain number of molecules of the liquid. This number will depend on the temperature and the chemical composition of the liquid. However, for a particular liquid, at a particular temperature, the average number of molecules escaping from the surface will always be the same and the pressure these molecules exert is called the vapour pressure of the liquid.

If evaporation can be checked totally, the temperature of a liquid will remain constant.

A) If the idea is stated in the passage

B) If the idea contradicts the contents of the passage

C) If the idea is not explicitly stated in the passage, but can be deduced from its contents

D) If the idea cannot be deduced from its content