A liquid is heated up to a certain temperature. Which one of the following situation would correspond to the boiling of the liquid?
[amp_mcq option1=”When atmospheric pressure becomes equal to the vapour pressure” option2=”When atmospheric pressure becomes less than vapour pressure” option3=”When atmospheric pressure becomes higher than the vapour pressure” option4=”When vapour pressure becomes equal to the air pressure” correct=”option1″]
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.