For p = KH x. Here KH is :

The correct answer is Option (2) → Henry’s Law constant

Henry’s law states that the partial pressure of a gas in the vapour phase (p) is proportional to the mole fraction of the gas (x) in the solution:

    \( \displaystyle p=K_H\,x \)

The proportionality constant K_H is Henry’s law constant. It depends on the nature of the gas and on temperature; the higher the K_H, the lower the solubility of the gas at a given pressure.

NCERT (2026-27 edition):
Solubility of a Gas in a Liquid – …

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 = K_H x … Here K_H is the Henry’s law constant.”