Which of the following statements about gases is false?

It is false that all gases are colorless and odorless at room temperature (option C below)

Explanation:

The answer choices are:

A) Gases expand spontaneously to fill the container they are placed in. B) Non-reacting gas mixtures are homogeneous C) All gases are colorless and odorless at room temperatune D) Distances between molecules of gas are very large compared to bond distances within molecules E) Gases are highly compressible.

Solution

Let's review each statement

A) Gases expand spontaneously to fill the container they are placed in.

This is correct. On of the properties of gases is that the particles (atoms or molecules) are not attracted to each other and can move freely. The gas substances do not have definite volume, but occupy all the space available, taking the form and volume of the container.

B) Non-reacting gas mixtures are homogeneous

This is correct. Since in a mixture of gases, every gas moves freely inside the container, the particles of all gases are intimately mixed without being able to physically distinguish one gas from another, which constitutes a homogeneous mixture.

C) All gases are colorless and odorless at room temperatune.

This is false. Some gases have color, some have odor, and some have both color and odor.

Some chemical reactions are evidenced when a color gas or a straneous olor evolves from the reaction.

For instance, the gases that evolve when food is rotten have a very unpleasant olor.

D) Distances between molecules of gas are very large compared to bond distances within molecules

This is correct. This is one of the assumptions of the molecular kinetic theory of gases that leads to the fact that gas molecules do not interact with each other and that the space occupied by the molecules themselves is negligible.

E) Gases are highly compressible.

This is correct. Since the gas particles are widely separated, most of the space in a gas is empty. Therefore, increasing the pressure, the empty space will decrease and the gas will occupy less volume. This is what compressible means: the volume can be reduced by applying pressure.