In terms of Charles' law explain why $–{273}^{\circ }C$ is the lowest possible temperature.

Charles’ law states that at constant pressure, the volume of a fixed mass of gas is directly proportional to its absolute temperature.

It was found that for all gases (at any given pressure), the plots of volume vs. temperature $\left(in{}^{\circ }C\right)$ is a straight line. If this line is extended to zero volume, then it intersects the temperature-axis at $–{273}^{\circ }C$. In other words, the volume of any gas at $–{273}^{\circ }C$ is zero.
This is because all gases get liquefied before reaching a temperature of $–{273}^{\circ }C$.

Hence, it can be concluded that $–{273}^{\circ }C$ is the lowest possible temperature.