Question

Which balanced equation represents a phase equilibrium?
(1) H2(g) + I2(g)<==> 2HI(g)
(2) 2NO2(g) <==> N2O4(g)
(3) Cl2(g) <==> Cl2(l)
(4) 3O2(g)<==> 2O3(g)

Answer 1

(3) Cl2(g) <==> Cl2(l), because it has an equilibrium between the two phases of liquid and gas.