If you extend your graph line all the
way to the left, you will notice that the line eventually crosses the
y-axis.
We call this temperature ABSOLUTE ZERO. Physicists
believe that at this temperature all motion of gas particles
stops. What would be the pressure at this temperature?
The pressure would be zero.
No one has been successful in lowering the temperature of gases
to this value, although physicists have come with a few
millikelvin of absolute zero.