Why should we use Kelvin temperature in gas law related problems?

Kelvin is an absolute temperature scale, which means that it defines "0" as the lowest possible energy state.

Now, when working with the , we're working under the assumption, thanks to the kinetic molecular theory, that the energies of gas particles depend on their temperature. As a result, we need to use Kelvin, because if we didn't, any temperature below zero would indicate a negative energy for the gas molecules, which doesn't happen.

OK.