Question

When air is saturated, it cannot hold _______________.
A. More water vapour
B. More air
C. More carbon dioxide
D. More oxygen

Answer 1

Hint:The gaseous substance present over the entire surface of the earth is said to be air. At a given temperature and pressure, a saturated substance is one that is unable to process or dissolve any more of another substance that is put into the given substance. Read the options carefully to recognize the factor that can saturate air.

Complete answer:
Air is the transparent gaseous material that surrounds the atmosphere and is primarily composed of oxygen and nitrogen. The term "unsaturated air" refers to air that holds relatively little water vapour content. Saturated air can be converted to unsaturated air by raising the temperature without changing the quantity (volume).

When the volume or quantity of 'water vapor' present in the air is at its highest limit at the current pressure and temperature, the air is considered to be saturated. When air absorbs the highest amount of moisture available at a certain temperature, it is considered to be saturated completely. Such a point is said to be 100 percent saturated when associated with humidity.

Let us look at each option carefully:
Option A ‘more water vapour’ is the correct option. For a given temperature, if the air contains the greatest quantity of water vapour, then the air at such a condition is considered to be saturated. So water vapour causes saturation to the air and so at a certain point air cannot hold more water vapour such a point is the point of saturation.

Option B ‘more air’ is an incorrect option. Air being a gaseous mixture, will remain the same when more air is added to it. The gaseous mixture does not experience an increase in any particular compound if air is added to air, hence in this case saturation is not possible.

Option C ‘more carbon dioxide’ is an incorrect option. Saturation of air means that it holds too much moisture content, so since carbon dioxide is a gas, it does not cause saturation to air. So we can reject this option because saturated will be able to hold more carbon dioxide.

Option D ‘more oxygen’ is an incorrect option. Air contains a good amount of oxygen content, so if more oxygen is added to air, it will cause changes to the surface of the earth but does not cause saturation since oxygen is not moisture. Hence we may reject this option because there is no proof that saturated air cannot hold more oxygen content.

Therefore the correct answer is option A.

Note:Air is said to be a solution because in chemistry, a solution is a uniformly formed mixture with more than one substance mixed in proportional quantities that can be continuously added till the solution has reached its highest point of solubility. While the word "solution" is most often associated with the state of liquid, there are solutions of solids and gases which can be formed.