Question

how did Charles law lead to the concept of absolute scale of temperature?

Answer 1

Charles's law is an experimental gas law that describes how gases tend to expand when heated. A modern statement of Charles's law is: When the pressure on a sample of a dry gas is held constant

Answer 2

Initially, Charles conducted some experiments to plot the variation of volume of a gas with the temperature, to study the relation between them when the other factors were kept constant ( pressure, no of moles and such). While doing so, when a graph was plotted between V and T, with volume in SI units and Temperature in Celsius, it turned out to be a straight line with a positive slope, but it cut the x axis at a point in the negative axis. This implied that in Celsius scale, zero volume could only be attained at that low temperature which turned out to be approximately - 273 Celsius. Hence, a new scale was adopted called Kelvin scale with - 273 C being the 0 of the Kelvin scale. This marked the absolute temperature which is the lowest temperature <possible>(not really) and hasn't been attained yet as at this point all molecular motion will cease and the gas will occupy zero volume while having mass which is Theoretically contradicting..