Select the correct statement/statements : (a) The chemical potential is a logarithmic function of its concentration (Activity) for dilute solutions and ideal gases. (b) Lowering of vapour pressure is not a colligative property of solution. (c) Osmosis does not involve semipermeable membrane and solvent. (d) In ideal solutions the solute and solvent obeys Raoult's law. Choose the most appropriate answer from the options given below :