Question 19
Change of State and VapoursWhich of the following conditions will make water boil at a temperature of 100°C when the atmospheric pressure is 750 mm Hg?
- A.Increase the external pressure
- B.Reduce the external pressure
- C.Heat more rapidly at the same pressure
- D.Reduce the external pressure by a quarter.
Show the answer and explanation
Answer: A (Increase the external pressure)
Explanation
Water boils at 100°C only at standard pressure, 760 mm Hg. At 750 mm Hg it boils below 100°C, so the pressure on it must be increased.