Which will have the lowest boiling point? pure water 0.5 m nacl (aq) 1.0 m nacl (aq) 2.0 m nacl (aq)

Option A = pure water

Explanation:

The pure water will have the lowest boiling point as compared to the other given solution.

Reason:

The pure water is just the solvent while other given options are solution which means that solute is present in it. The vapor pressure of the solvent goes to decrease when solute is added.  Thus boiling point is increases because more heat is needed in order to create the vapor pressure equal to the external pressure.

The boiling points of solvents thus changes above the solution as the concentration of solute varies. In given solutions the 2.0 m NaCl will have highest boiling point because of high concentration of sodium chloride while 0.5 m NaCl will have lowest boiling point after the pure water.

Mathematical expression:

              ΔT = Kbm

ΔT = change in the boiling point

Kb = Boiling point elevation constant

m = molal  concentration of solute

The change in the boiling point of solvent above solution will directly proportional to the solute concentration.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-