<P> Or Boyle's law is a gas law, stating that the pressure and volume of a gas have an inverse relationship, when temperature is held constant . If volume increases, then pressure decreases and vice versa, when temperature is held constant . </P> <P> Therefore, when the volume is halved, the pressure is doubled; and if the volume is doubled, the pressure is halved . </P> <P> Boyle's law states that at constant temperature for a fixed mass, the absolute pressure and the volume of a gas are inversely proportional . The law can also be stated in a slightly different manner, that the product of absolute pressure and volume is always constant . </P> <P> Most gases behave like ideal gases at moderate pressures and temperatures . The technology of the 17th century could not produce high pressures or low temperatures . Hence, the law was not likely to have deviations at the time of publication . As improvements in technology permitted higher pressures and lower temperatures, deviations from the ideal gas behavior became noticeable, and the relationship between pressure and volume can only be accurately described employing real gas theory . The deviation is expressed as the compressibility factor . </P>

What type of relationship do pressure and volume have