Chemistry - Chemical Equilibrium Question with Solution | TestHub

\begin{gathered}{}\text{P}_{\text{H2O}}\text{ }\text{=}\text{ }\surd\text{(1.21}\times\text{10}^{\text{-4}}\text{)}\text{ }\text{=}\text{ }\text{1.1}\times\text{10}^{\text{-2}}\text{ }\text{atm}\text{ }\text{=}\text{ }\text{8.36}\text{ }\text{torr}\text{ }\text{Relative}\text{ }\text{humidity}\text{ }\text{=}\text{ }\text{8.36/40}\times\text{100}\text{ }\\{}\text{=}\text{ }\text{20.9%}\\{}\text{Efflorescence}\text{ }\text{occurs}\text{ }\text{when}\text{ }\text{the}\text{ }\text{water}\text{ }\text{vapour}\text{ }\text{pressure}\text{ }\text{in}\text{ }\text{air}\text{ }\text{is}\text{ }\text{below}\text{ }\text{the}\text{ }\\{}\text{equilibrium}\text{ }\text{value.}\\{}\text{So}\text{ }\text{the}\text{ }\text{salt}\text{ }\text{effloresces}\text{ }\text{at}\text{ }\text{relative}\text{ }\text{humidity}\text{ }\text{below}\text{ }\text{20.9%.}\\{}\text{This}\text{ }\text{is}\text{ }\text{option}\text{ }\text{(d).}\end{gathered}