In terms of Charles’ law explain why –273°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.

From the above graph between V and T we can find that at constant pressure if temperature is lowered, there is also a decrease in the volume at constant pressure. The volume should therefore become zero at –273°C. Any further lowering is impossible as it will imply negative volume. Hence, –273°C is the lowest possible temperature.