Luster is a characteristic physical property of metals, but some non-metals also exhibit a shiny appearance. Iodine is a non-metal that forms dark purple, lustrous crystalline solids. Sulphur is dull yellow, phosphorus is white/red and waxy, and carbon (as graphite/coal) is generally dull.
Explanation:
Phenolphthalein is colorless in acidic and neutral solutions (pH < 8.3) and turns pink to deep red in basic solutions (pH > 10). Methyl orange is red in acid, yellow in base. Litmus is red in acid, blue in base. Turmeric is yellow in acid, reddish-brown in base.
Explanation:
Temporary hardness is due to dissolved bicarbonates of Ca and Mg, which can be removed by boiling: Ca(HCO₃)₂ → CaCO₃↓ + H₂O + CO₂. Permanent hardness is caused by chlorides and sulfates of Ca and Mg, not removed by boiling. Sodium bicarbonate does not cause hardness. Methods to remove permanent hardness include treatment with washing soda (Na₂CO₃), ion exchange, or calgon.
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