Keisha finds instructions for a demonstration on gas laws.
1. place a small marshmallow in a large plastic syringe.
2. cap the syringe tightly.
3. pull the plunger back to double the volume of gas in the syringe.
which best describes the purpose and outcome of the demonstration?

The correct answer is option C. This is a demonstration of Boyle’s law. As the volume increases, the pressure decreases, and the marshmallow will grow larger. 

 Keisha follows the instructions for a demonstration on gas laws.
 1. Place a small marshmallow in a large plastic syringe.
 2. Cap the syringe tightly. 
 3. Pull the plunger back to double the volume of gas in the syringe.

Now, this activity is being done at the same temperature, because there is no mention of the temperature change.  Thus, when the plunger is pulled back, the volume doubles, so pressure will decrease. Therefore, This is a demonstration of Boyle’s law. As the volume increases, the pressure decreases, and the marshmallow will grow larger.