Temporary hardness of water can be removed by: MCQ with Answer and Explanation

Explanation:
NaCl + H₂SO₄ (conc.) → NaHSO₄ + HCl↑, at low temperature. At high temperature, NaHSO₄ + NaCl → Na₂SO₄ + HCl. This is the laboratory preparation of HCl gas. Industrial production is by direct combination of H₂ and Cl₂. Nitric acid is an oxidizer and would produce chlorine. Sodium hydroxide gives salt and water (neutralization). Ammonia reacts with acid.

Explanation:
Rhizobium bacteria form root nodules in leguminous plants (peas, beans, clover) and fix atmospheric N₂ into ammonia, providing nitrogen to the plant, while the plant supplies carbohydrates. Azotobacter and Azospirillum are free-living nitrogen fixers. Pseudomonas is a general soil bacterium. Symbiotic association is mutualistic. Inoculating seeds with Rhizobium culture increases soil fertility.

Explanation:
An electrolyte is a substance that produces ions when dissolved in water or melted, allowing the solution to conduct electricity. Aqueous NaCl dissociates into Na⁺ and Cl⁻ ions. Distilled water, sugar, and ethanol do not form ions in solution and are therefore non-electrolytes.