# Which of the following expression acquires constant value at equilibrium for the process shown below?

$Liquid \rightleftharpoons Vapour$

$H_{2}O (l) \rightleftharpoons H_{2}O (g)$

(a) Pressure

(b) Solubility

(c) Temperature

(d) $p H_{2}O$

Toolbox:
• In case of a $Liquid \rightleftharpoons Gas$ equilibrium, the pressure of the vapour above the liquid becomes constant at a particular temperature.