Which has the lowest freezing point?
a).pure water
b).0.5 m ionic nacl
c).0.5 m ionic cacl2
d).0.5 m ionic alcl3
e).0.5 m molecular c12h22o11

0.5 M ionic

Explanation: Addition of nonvolatile solute depresses the freezing point of a solvent. As depression in freezing point is a colligative property, which means it depends on the amount of solute. Thus more is the no of ions, more is the depression in freezing point.

=Depression in freezing point

= freezing point constant

m= molality

a) pure water: It is a pure solvent and freezes at 0 ° C.

b) 0.5M ionic NaCl:

, it produces two ions, each of concentration 0.5M. The total concentration of ions is 1.0 M.

c) 0.5 M ionic

, it produces two ions, of concentration 0.5M and of concentration . The total concentration of ions is 1.5 M.

d) 0.5 M ionic

, it produces two ions, of concentration 0.5 M and of concentration The total concentration of ions is 2.0 M.

e) 0.5 M molecular

It is a covalent compound and do not dissociate into ions. thus the concentration will be 0.5 M only.

As the concentration of ions is highest in 0.5 M ionic , the depression in freezing point is highest ans thus it has lowest freezing point.

c is the answer because when something is left after something evaporates that shows the chemical change.

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