The permanent hardness of water can be removed by adding:
A. Baking soda
B. Soda ash
C. Washing soda
D. Caustic soda
Answer: Option C
Solution (By JKExamLibrary)
Permanent hardness is caused by dissolved chlorides and sulfates of calcium and magnesium. It cannot be removed by boiling. It is removed by adding washing soda (sodium carbonate, Na2CO3). The carbonate ions react with the soluble calcium and magnesium salts to form insoluble carbonates, which precipitate out.
Explanation:
Phenolphthalein is colorless in acidic and neutral solutions, turning pink/magenta in basic solutions with pH > about 8.2-10. It is commonly used in acid-base titrations. Methyl orange is red in acidic and yellow in basic. Litmus is purple in neutral, red in acid, blue in base. Natural indicators like turmeric, beetroot also show color changes.
Explanation:
Fermentation is an anaerobic biological process in which enzymes (zymase) convert glucose to ethanol and CO₂: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Oxidation would require oxygen. Esterification forms esters, saponification makes soap. Fermentation is used in brewing, winemaking, and baking (where CO₂ makes bread rise). The temperature is kept around 30-35°C.
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