Here, we have provided the NCERT Exemplar for Class 12 Chemistry, Chapter 2: Solutions.
Question 1. Which of the following unit is useful in relating concentration of solution with its vapour pressure?(a) Mole fraction (b) Parts per million (c) Mass percentage (d) Molality
Solution: (a) Mole fraction is useful in relating vapour pressure with concentration of solution. According to Raoult’s law, the partial vapour pressure of each component in the solution is directly proportional to its mole fraction. A is one component.
Question 2. On dissolving sugar in water at room
temperature solution feels cool to touch. Under which of the following case
dissolution of sugar will be most rapid?
(a) Sugar crystals in cold water (b) Sugar
crystals in hot water
(c) Powdered sugar in cold water (d) Powdered
sugar in hot water
Solution: (d) The solution feels cool to the touch, so the dissolution is endothermic. This means higher temperatures will help it dissolve better. Also, powdered sugar dissolves easily because it has a large surface area.