3: Solubility

Correct answer: B. About 10 g solute may separate

Explanation: At the stated temperature, 45 g is the normal equilibrium limit for 100 g water, but 55 g is present. The solution is therefore supersaturated by about 10 g. A seed crystal provides a nucleation surface, so excess solute may crystallize until roughly the normal limit remains dissolved. The exact separated amount can depend on conditions.

Correct answer: A. आयनिक गुणनफल बढ़ सकता है

Explanation: The ionic product is calculated from the current concentrations of the ions. Adding a common ion raises one ion concentration, so the ionic product can become greater than Ksp. When Q exceeds Ksp, the solution is supersaturated with respect to that salt and precipitation proceeds until Q returns to Ksp. Ksp itself is not made infinite by adding an ion.

Correct answer: B. अधिक घुलनशीलता

Explanation: For salts having the same dissolution stoichiometry, the expression for Ksp has the same powers of solubility for both salts. A larger Ksp then corresponds to a larger equilibrium solubility and hence greater dissolution. This conclusion cannot be applied blindly to salts with different ion ratios, because their Ksp expressions contain different powers and direct numerical comparison becomes misleading.

Correct answer: A. Balance of hydration and lattice energies

Explanation: Dissolving an ionic solid requires separating ions from the crystal lattice, which costs lattice energy. Water molecules then hydrate and stabilise the separated ions, releasing hydration energy. Solubility depends on the overall energy and entropy balance, not on charge alone. If hydration is insufficient to offset lattice forces, the solid may be only slightly soluble.

Correct answer: A. Gas solubility decreases

Explanation: Using p = K_H x, at a fixed pressure a decrease in gas solubility means a decrease in dissolved mole fraction x. Since K_H = p/x, a smaller x produces a larger K_H. Gas solubility generally decreases with rising temperature, so the Henry constant commonly increases, though the exact temperature dependence is system-specific.

Correct answer: A. Apply Henry’s law

Explanation: The combination of a gas dissolved in a liquid, its pressure, and mole fraction is the standard clue for Henry’s law. Write p = K_H x, identify the known quantities, and rearrange if necessary. Temperature should not be ignored because K_H depends on it. Lattice energy applies mainly to ionic solids, while colour provides no relevant equation.