Hard water does not lather well with soap because it forms: MCQ with Answer and Explanation

Explanation:
Chlorophyll, the green pigment in plants, contains a magnesium ion (Mg²⁺) at the center of the porphyrin ring. It's essential for photosynthesis. Haemoglobin in blood contains iron. Calcium is in bones. Sodium is in body fluids.

Explanation:
Limestone is CaCO₃. On strong heating, it decomposes to calcium oxide (quicklime) and carbon dioxide: CaCO₃ → CaO + CO₂. This is a decomposition reaction used in cement and lime manufacturing. CaO is used in building and as a drying agent.

Explanation:
Organic fertilizers (compost, manure, bone meal) add humus, improving soil structure, water retention, and aeration. They support beneficial microorganisms that slowly decompose organic matter, releasing nutrients gradually. Unlike synthetic fertilizers, they do not cause sudden nutrient spikes or soil acidification. Biofertilizers like Rhizobium fix nitrogen. Organic farming emphasizes sustainability and reduced chemical inputs.