Malik is investigating the properties of helium. Malik finds the chart below about helium in a textbook.
The table shows information about helium. To be in a solid state, helium must be under extreme pressure. To be in a liquid state, helium must be at negative 273 degrees celsius. To be in a gas state, helium must be at room temperature of about 21 degrees celsius.
Malik uses models to study helium as different states of matter. He also investigates the motion of helium molecules.
Multiple Choice Question
Malik draws a model to explain changes of state for helium as shown.
From left to right, the illustration shows three boxes labeled 'solid', 'liquid' and 'gas'. An arrow labeled 'Step X' points from gas to liquid. Another arrow points from liquid to solid.
Step X describes how helium gas could become a liquid. Which of the following could be the label for Step X?
A.
Thermal energy is removed and molecular motion increases.
B.
Thermal energy is added and molecular motion decreases.
C.
Thermal energy is added and molecular motion increases.
D.
Thermal energy is removed and molecular motion decreases.
1 answer
To determine the correct label for Step X, which describes how helium gas could become a liquid, we need to consider the process of condensation.
When a gas transforms into a liquid, thermal energy is removed from the gas, causing the molecules to lose energy and move closer together as their motion decreases.
Thus, the correct answer is:
D. Thermal energy is removed and molecular motion decreases.
