Concept:Vapour pressure lowering is a colligative property and depends only on the number of solute particles present.
Explanation:Maximum vapour pressure corresponds to minimum lowering of vapour pressure.
Minimum lowering occurs when the number of solute particles in solution is least.
For
1M solutions, count the particles produced per formula unit:
NaCl→Na++Cl−, so particles
=2.
CaCl2→Ca2++2Cl−, so particles
=3.
AlCl3→Al3++3Cl−, so particles
=4.
Sucrose,
C12H22O11, does not dissociate in water, so particles
=1.
Since sucrose gives the least number of solute particles, it causes the least lowering of vapour pressure.
Therefore, it shows the maximum vapour pressure at
300K.
Answer:Option D:
1MC12H22O11