212) When sulphur is in the form of S₈ is heated at 900 K, the initial pressure of 1 atm falls by 29% at equilibrium. This is because of conversion of some S₈ to S₂. Find the value of equilibrium constant for this reaction:

213) What is the approximate OH⁻ ion concentration of a 0.15M NH₃ solution? (K_a = 1.75 x 10⁻⁵)

214) The vapour density of PCl₅ is 104.25 but when heated to 230^oC, its vapour density at this temperature will be:

215) When ammonia is added to pure water, the concentration of which of the following species already present, will decrease?

216) The equilibrium constant K_p for a homogeneous gaseous reaction is 10⁻⁸. The standard Gibb′s free energy change, ΔG^o for the reaction is: