At what temperature will the pressure be equal to zero kPa in degrees Celsius?

Pressure cannot truly be equal to zero kPa at any temperature as pressure is defined as the force exerted by particles as they collide with the walls of their container. According to the kinetic theory of gases, as long as there are gas particles moving and colliding with the walls of a container, there will be some pressure exerted. In theory, the pressure would only be at zero kPa if the temperature were to reach absolute zero, which is -273.15 degrees Celsius. This is an unattainable temperature since it is the point where all particle motion stops, according to the Third Law of Thermodynamics. However, in practice, it's impossible to remove all energy from a system to reach absolute zero, so we can never actually observe a pressure of zero kPa due to a finite temperature.

Extra: The relationship between temperature and pressure for a given volume of gas is described by Gay-Lussac's Law, which states that the pressure of a gas is directly proportional to its temperature when the volume is held constant. Mathematically, this is often written as P/T = k, where P is pressure, T is temperature, and k is a constant. This means that if you double the absolute temperature (measured in kelvins), you double the pressure.

To understand why the pressure would theoretically reach zero at absolute zero, we have to look at the kinetic molecular theory of gases. This theory says that the temperature of a gas is a measure of the average kinetic energy of its particles, and that the pressure is a result of collisions between these particles and the walls of their container. If you lower the temperature, the particles move more slowly, and the frequency and energy of their collisions with the container walls decrease, leading to lower pressure. If you could lower the temperature to absolute zero (-273.15°C), there would be no particle motion, and thus no collisions to exert pressure. However, as mentioned before, reaching absolute zero is not physically possible.