Ice (solid H₂O) is a molecular solid where molecules are held together by hydrogen bonds and van der Waals forces. Diamond is a covalent network solid. NaCl is ionic solid. Iron is metallic solid. Molecular solids have low melting points, are soft, and are poor conductors. Other examples: dry ice (CO₂), iodine, sugar.
Explanation:
Excessive use of chemical fertilizers, especially those containing nitrogen and phosphorus, can lead to runoff into water bodies. This causes eutrophication (algal blooms), which depletes oxygen in the water and kills aquatic life. It also degrades soil health and kills beneficial microbes over time.
Explanation:
Faraday's first law of electrolysis: Mass of substance deposited or liberated is proportional to the charge passed (m = ZQ). Z is electrochemical equivalent. Second law relates masses of different substances to equivalent weights for same charge. Ohm's law is V=IR, Graham's law for diffusion. Faraday's laws are quantitative.
Explanation:
Iodine directly converts from solid to violet vapor on gentle heating (sublimation). NaCl melts; sugar decomposes; copper melts at high temperature. Other sublimable substances: camphor, naphthalene, dry ice.
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