Question

Which of the following statements are true? Check all that apply. View Available Hint(s) Check all that apply. The average speed of gas molecules decreases with decreasing temperature. The kinetic energy of a molecule cannot determine its speed. All the gas molecules in a sample cannot have the same kinetic energy. The average kinetic energy of gas molecules decreases with decreasing temperature. There are gas molecules that move slower than the average.

Answer 1

The second one is not true

Answer 2

Answer:

1. The average speed of gas molecules decreases with decreasing temperature.
2. The average kinetic energy of gas molecules decreases with decreasing temperature.
3. There are gas molecules that move slower than the average.

Explanation:

The average speed of gas molecules decreases with decreasing temperature.

Gas molecules are directly affected by temperature, actually, it's an important property of gas, because it determines other variables like pressure and volume, which is also related with the speed of molecules. When we heat a gas, molecules are gonna be more excited, which means that they are gonna move more and faster, so, basically temperature determines the average speed of molecules. If the temperature increases, the average speed increases as well, if the temperature decreases, the average speed decreases, because the molecules are gonna move less.

The average kinetic energy of gas molecules decreases with decreasing temperature.

This effect is similar to the relation between speed and temperature. The average kinetic energy of gas molecules is also directly proportional to temperature. Mainly because the kinetic energy depends on the speed, if the speed decreases, the kinetic energy decreases as well. Therefore, with decreasing temperature, the average speed decreases, and the average kinetic energy also decreases. You can figure this out from the equation of kinetic energy:

$K=\frac{1}{2}mv^{2}$

There are gas molecules that move slower than the average.

This statement is always true. The cinematic of gas molecules is treated by average stats, because inside certain volume of gas there are thousands of molecules, which cannot be studied one by one. So, to solve that problem in that micro context we recur to average magnitudes.

In addition, when we use average magnitudes, we acknowledge that the result it represents a majority of molecules but not all of them, this means that there are molecules below or above the average. That's why there are always gonna be molecules with slower speed. Basically, the average is just a middle point.