When zeolite, which is hydrated sodium aluminium silicate is treated with hard water the sodium ions are exchanged with

The freezing point of equimolal aqueous solutions will be highest for

The vapour pressure of pure benzene at a certain temperature is 640 mm Hg. A non-volatile non-electrolyte solid weighing 2.175 g is added to 39.0 g of benzene. The vapour pressure of the solution is 600 mm Hg. What is the molecular weight of the solid substance?