Solutions practice · Easy

Option C ($A - B$ attraction force remains same as $A - A$ and $B - B$) is correct because this is the condition for a solution to follow Raoult's law.

Option A (Moist air) is correct because it contains water (liquid) dispersed in air (gas).

Camphor has a high molal depression constant, which leads to a significant depression in freezing point even for small amounts of solute, making option C the correct answer. This makes it suitable for determining the molecular weight of non-volatile solutes using the Rast method.

Option B ($BaC{l_2}$) is correct because it dissociates into 3 ions, resulting in the highest van't Hoff factor and thus the maximum boiling point elevation.

Option C is correct because the molality is calculated using the formula $\Delta T_f = K_f \times m$, where $\Delta T_f$ is the freezing point depression, $K_f$ is the cryoscopic constant, and m is the molality.

Option A is false because freezing point depression depends on the solvent's cryoscopic constant ($K_f$), which varies with the solvent.

Option A ($2/3$) is correct because the relative vapor pressure is calculated using Raoult's Law, considering the mole fractions of the solute and solvent.

The vapor pressure of a solvent is lowered when a non-volatile solute is added, making option B the correct answer. This is due to fewer solvent molecules being able to escape into the vapor phase.

Option B (Vaporization) is correct because increasing the temperature favors the phase transition from liquid to gas, which is vaporization.

Plant cells act as natural semipermeable membranes, allowing water and small molecules to pass through while restricting larger molecules, making option C the correct answer.

Option D (300) is correct because it is calculated by equating the osmotic pressures of the urea solution and the non-volatile solute solution.

Option A (Molar mass) is correct because colligative properties directly relate to the number of solute particles, which is used to determine molar mass.

Option C (Lattice energy) is correct because lattice energy is the energy that opposes the dissolution of a solute in a solvent, especially for ionic compounds.

Option A (9N) is correct because the normality of an acid is its molarity multiplied by its basicity (number of replaceable H⁺ ions), and orthophosphoric acid (H₃PO₄) has a basicity of 3.

Option C (2.3077%) is incorrect. Option A (2.3077) is correct because molality is calculated by finding the mass of the solvent and then dividing the moles of solute by the mass of the solvent in kg.

Option A (Hydration energy) is correct because hydration energy is the energy released when ions are surrounded by water molecules, favoring dissolution.

Option A ($\Delta \mathrm{V}=+\mathrm{ve}, \Delta \mathrm{H}=+\mathrm{ve}$) is correct because positive deviations from Raoult's law indicate weaker intermolecular forces in the solution, leading to an increase in volume and endothermic mixing.

Option B is correct because while molality is indeed temperature independent, the molarity changes with temperature due to volume changes, and therefore, 1 M and 1 molal solutions of the same solute do not contain the same mass of solute, but the reason is still true.

Option D (All of the above) is correct because the solubility of a gas in a liquid is affected by the nature of the gas, the nature of the solvent, temperature, and pressure.

Option D (All of these) is correct because the solubility of calcium hydroxide, sodium carbonate, and sodium sulfate all decrease with increasing temperature.

Option D (The number of solute particles) is correct because colligative properties depend only on the number of solute particles, not their identity.

Option D ( Benzene in water) is correct because benzene and water are immiscible and do not form a true solution; instead, they form a heterogeneous mixture.

Option C is correct because the vapor pressure of a liquid, including water, is primarily dependent on temperature. Higher temperatures increase the kinetic energy of molecules, allowing more of them to escape into the vapor phase.