KCET 2025 Chemistry Paper

To determine which 0.1 m aqueous solution will have the lowest boiling point elevation, we need to consider the Van't Hoff factor (i). This factor represents the number of particles the compound dissociates into in solution. The formula for boiling point elevation, ∆Tb∝i, indicates that a higher i value leads to a greater elevation in boiling point.
Here are the values of i for each compound, assuming complete ionization:
Aluminium chloride (AlCl3):i=4
Aluminium sulfate (Al2(SO4)3):i=5
Potassium sulfate (K2SO4):i=3
Sodium chloride (NaCl): i=2
The solution with the lowest i value will exhibit the smallest increase in boiling point. Therefore, sodium chloride, which has i=2, will show the lowest boiling point elevation among the options.