Question

The vapour pressure will be lowest for

• A. 0.1 M sugar solution
• B. 0.1 M KCl solution
• C. 0.1 M Cu(NO₃)₂ solution
• D. 0.1 M AgNO₃ solution

Answer 1

The correct option is C

0.1 M Cu(NO₃)₂ solution

Vapour pressure of a solvent is lowered by the presence of solute in it. Lowering in vapour pressure is a colligative property i.e., it depends on the no. of particles present in the solution. Cu(NO₃)₂ give the maximum no. of ions. (i.e., 3) so it causes the greatest lowering in vapour pressure of water.