A solution of potassium iodide and HgI2 has higher vapour pressure. Why?

CBSE Class 12
1

A solution of potassium iodide and HgI2 has higher vapour pressure. Why?

2

KI forms a complex with HgI2.
2KI + HgI2 → K2HgI4
Therefore, the number of particles in solution decreases resulting in the decrease in relative lowering of vapour pressure. Hence, vapour pressure increases.