Solutions

Water is polar, and methane is the most soluble in water due to its smaller size and the potential for weak interactions with water molecules.

Molarity (M) is the number of moles of solute per liter of solution. 1 M NaCl is the most concentrated solution when compared to the others in the options.

We can use Raoult's Law for ideal solutions: where: - is the total vapour pressure of the solution, - is the vapour pressure of benzene in the solution, - is the vapour pressure of toluene in the solution. Raoult's law states: where and . Let the mole fraction of benzene be and the mole fraction of toluene be . From Raoult's law: We know , so: Also, since , we substitute into the equation: Simplifying the equation: Thus, the mole fraction of benzene is 0.2, and the mole fraction of toluene is 0.8.
Thus, the correct answer is (d).

The deep blue color observed when sodium is dissolved in liquid ammonia is due to the presence of solvated electrons.
These electrons are free to move within the solution, creating the characteristic color.
This phenomenon occurs because sodium metal dissociates to produce Na ions, leaving behind free electrons that are solvated by ammonia molecules.

We can use the dilution formula , where , , , and is the final volume. Solving for : So, the volume of water to be added is: Thus, the correct answer is (d).