A liquid is heated up to a certain temperature. Which one of the following situation would correspond to the boiling of the liquid?
When atmospheric pressure becomes equal to the vapour pressure
When atmospheric pressure becomes less than vapour pressure
When atmospheric pressure becomes higher than the vapour pressure
When vapour pressure becomes equal to the air pressure
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-2 – 2023
– The boiling point of a liquid is defined as the temperature at which its vapor pressure equals the surrounding environmental pressure (usually atmospheric pressure).
– At this point, the vapor pressure is sufficient to overcome the external pressure, allowing bubbles of vapor to form within the bulk of the liquid and rise to the surface.
– If atmospheric pressure is higher than the vapor pressure, boiling will not occur at that temperature; the liquid must be heated further to increase its vapor pressure to match the higher external pressure.
– Option D essentially states the same condition as option A, assuming “air pressure” refers to the external pressure, which is typically atmospheric pressure in an open system. Option A uses the more standard terminology.