Final answer:
When plotting V (volume) against 1/P (pressure), you get a straight line because it represents an inverse relationship, such as Boyle's Law.
Step-by-step explanation:
When plotting V (volume) against 1/P (pressure), you get a straight line. This type of relationship is known as an inverse relationship, where one variable increases while the other variable decreases in a proportional manner. In this case, as pressure decreases, the volume increases. An example of this is Boyle's Law, which states that at a constant temperature, the pressure and volume of a gas are inversely proportional.