The partial pressure of the gas in vapour phase (P) is proportional to the mole fraction of the gas (x) in the solution. It is expressed as P = KHx.
KH stands for-
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Henry’s law constant
Henry’s law describes the solubility of a gas in a liquid: the partial pressure of the gas in the vapour phase is proportional to its mole fraction in the solution.
\( \displaystyle p = K_H\,x \)
The proportionality constant KH is the Henry’s law constant. It depends on the nature of the gas and on temperature; the higher the KH at a given pressure, the lower the solubility of the gas.
NCERT (2026-27 edition):
Solubility of a Gas in a Liquid – “… The most commonly used form of Henry’s law states that “the partial pressure of the gas in vapour phase (p) is proportional to the mole fraction of the gas (x) in the solution” and is expressed as:
p = KH x (1.11)
Here KH is the Henry’s law constant.”