Which of the following acids is considered a strong acid?
A. Carbonic acid
B. Acetic acid
C. Citric acid
D. Hydrochloric acid
Answer: Option D
Solution (By JKSSB Mock Tests)
Hydrochloric acid (HCl) dissociates completely in water, making it a strong acid. Acetic acid (CH₃COOH), carbonic acid (H₂CO₃), and citric acid are weak acids—they partially ionize. Other strong acids: H₂SO₄ (first dissociation), HNO₃, HBr, HI, HClO₄. Strong acids have very large Ka values. pH of 0.1 M HCl is about 1.
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:
Amorphous solids like glass do not have a sharp melting point; they soften over a range of temperatures. Crystalline solids have sharp melting points and long-range order. Glass is an insulator.
Explanation:
Yeast (Saccharomyces cerevisiae) enzymes convert glucose to ethanol and CO₂ anaerobically. Bacteria produce lactic acid or acetic acid; algae are photosynthetic.
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