Final answer:
A system may fail to hold a vacuum after evacuation due to moisture inside the system or a physical leak. Vacuum pumps remove air to create a vacuum, and O-rings seal joints to maintain it. Lowered pressure in a vacuum can cause water to boil at room temperature.
Step-by-step explanation:
The possible cause for a system that fails to hold a vacuum after the evacuation process might include the presence of moisture or a leak. Moisture can vaporize and increase the pressure inside the system, negating the vacuum. Likewise, a leak can allow air to enter, which disrupts the vacuum.
The vacuum pump is designed to remove gas molecules from the system, lowering the pressure to create a vacuum. When the vacuum pump is turned on, it starts evacuating air, creating a pressure lower than atmospheric pressure.
An O-ring is a sealing component used in many devices which performs a critical function. The role of the O-ring is to seal the joining of two parts to prevent the escape of fluids or gases, thus ensuring the vacuum can be maintained in a system without air or other contaminants getting in.
As for the temperature at which water boils, it is affected by the pressure of the surrounding environment. In a vacuum, where the pressure is significantly lower than atmospheric pressure, water can boil at room temperature, which is significantly lower than the usual boiling point of 100°C. At less than approximately 20 mm Hg, water can boil at 40.0°C.