Group 18 elements are noble gases: helium, neon, argon, krypton, xenon, radon. They have completely filled valence shells, making them chemically inert (though xenon can form compounds). Nitrogen is Group 15, Oxygen Group 16, Hydrogen is unique (Group 1).
Explanation:
Ozone (O₃) has one coordinate bond; a central oxygen donates a lone pair to another oxygen. CH₄, NH₃, H₂O have ordinary covalent bonds, though NH₃ can donate a pair to form NH₄⁺.
Explanation:
Global warming, caused by increased greenhouse gases, leads to melting of polar ice, thermal expansion of oceans, rise in sea level, and changes in weather patterns (climate change). It does not cool the Earth or decrease CO₂.
Explanation:
Fermentation is the anaerobic breakdown of glucose by enzymes (zymase) in yeast to produce ethanol and CO₂: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Esterification forms esters, saponification makes soap, hydrogenation adds H₂.
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