0°C on the Celsius scale is equal to 273.15 K on the absolute scale.

The Kelvin scale of temperature is also called  Thermodynamic scale of temperature 

To obtain a temperature at the Kelvin scale, add 273 (more precisely 273.15) to the Celsius temperature.

Charles found that for all gases, at any given pressure, graph of volume vs temperature (in Celsius) is a straight line and on extends to zero volume each line in the volume- temperature graph intercepts the temperature axis at – 273.15 °C

Each line of the volume vs temperature graph is called isobar

The volume of the gas at – 273.15 °C will be zero

Gas will not exist at – 273.15 °C

Charles law gives the relationship between volume and temperature

The volume of a gas increases on increasing temperature and decreases on cooling.

Volume of a gas increases by 1/273.15 of the original volume of the gas at 0 °C for each degree rise in temperature,

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

 Volume vs temperature (Kelvin) graph at constant pressure  is called an isobar.