The substance when dissolved in water would decrease the vapour pressure of water to the greatest extent is:-

Assertion:- The molality of the solution doesn't change with change in temperature.

Reason:- The molality is expressed in units of moles per $1000 \mathrm{mL}$ solution.

Assertion:- The sum of the mole fraction of all the components is unity.

Reason:- Mole fraction is a temperature dependent mode of concentraction.

Assertion:- A solution which contains one gram equivalent of solute per litre of the solution is called normal solution.

Reason:- A normal solution mean a solutions in which the solute doesn't associate or dissociate.

Assertion:- The molarity and normality of a solution of sodium carbonate are same.

Reason:- Normality is the product of molarity and valency factor.

Assertion:- Ideal solutions are one which obeys Raoult's law at all temperature and concentration.

Reason: -Very dilute solution can be treated as ideal solution.

Assertion: - In positive deviation of non-ideal solution attraction between solute solvent is less than the attraction between solute-solute and solvent-solvent.

Reason:-In negative deviation of non-ideal solution attraction between solute-solvent is more than the attraction between solute-solute and solvent-solvent.