Final answer:
If half of the gas is removed from an isothermal container initially at 200 KPa, the pressure becomes 100 KPa.
This conclusion is based on the direct proportionality between the number of gas particles and pressure at constant volume and temperature.
Step-by-step explanation:
When dealing with gases, one important principle is that the pressure exerted by a given amount of gas is proportional to the number of particles if the volume and temperature are held constant.
This is derived from the ideal gas law, which is written as PV = NkT, where P is pressure, V is volume, N is number of particles, k is Boltzmann's constant, and T is temperature.
In the scenario provided, the gas is contained in an isothermal container meaning the temperature (T) is constant. If we remove half of the gas while keeping the volume and temperature constant, the pressure (P) will also be halved.
Therefore, if the initial pressure was 200 KPa, removing half of the gas would result in a new pressure of 100 KPa.