Q1: For most salts, the solubility increases with rise in temperature, but the solubility of __________ is nearly independent of temperature rise.

ANS:A - sodium chloride

For sodium chloride (NaCl), its solubility does indeed increase with a rise in temperature. This phenomenon is observed in many salts, including NaCl, and is due to the fact that increasing temperature provides more energy to overcome the intermolecular forces holding the solid salt particles together, allowing more salt to dissolve in the solvent (usually water). The increase in solubility with temperature for sodium chloride and similar salts is attributed to the endothermic dissolution process. As temperature rises, the kinetic energy of the solvent molecules increases, leading to more frequent and energetic collisions with the solid salt particles. This increased energy disrupts the intermolecular forces between the Na⁺ and Cl⁻ ions in the crystal lattice of sodium chloride, promoting their separation and dissolution into the solvent. However, there are exceptions to this general trend. For instance, some salts, like anhydrous sodium sulfate (Na₂SO₄), exhibit solubility behavior that is nearly independent of temperature rise, as mentioned earlier. This can be due to various factors such as changes in hydration state, complex formation, or specific interactions with the solvent molecules. In summary, while the solubility of sodium chloride increases with a rise in temperature, it's important to note that different salts may exhibit different solubility behaviors depending on their chemical and physical properties.