Final answer:
In an experiment examining the effect of changing gas volume on pressure, the pressure is the dependent variable, changing in response to volume alterations.
Step-by-step explanation:
When considering the research question, "Does changing the volume of a gas affect the pressure?", the dependent variable in the experiment is the pressure of the gas. This is because, according to the principles of gas laws, such as Boyle's Law, the pressure is the variable that responds to changes in the volume of the gas when the temperature and amount (number of moles) of the gas are held constant. To clarify, when the volume of a contained gas is increased, the pressure decreases, and conversely, when the volume is decreased, the pressure increases. This inverse relationship is an essential concept in understanding gas behaviors under different conditions.