The pH of pure water at 25°C is 7. This is because: MCQ with Answer and Explanation

The pH of pure water at 25°C is 7. This is because:
A. It is a strong acid
B. It contains equal concentrations of H⁺ and OH⁻ ions
C. It contains only OH⁻
D. It has no ions
Answer: Option B
Solution (By JKSSB Mock Tests)
Water self-ionizes: H₂O ⇌ H⁺ + OH⁻. At 25°C, [H⁺] = [OH⁻] = 10⁻⁷ mol/L, so Kw = 10⁻¹⁴ and pH = pOH = 7. A solution is neutral when [H⁺] = [OH⁻]. pH 7 is neutral only at 25°C; at higher temperatures, Kw increases, pH of neutrality drops but still [H⁺]=[OH⁻].

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Question #1
Which of the following methods is used to obtain pure copper from impure copper?
A. Electrolytic refining
B. Roasting
C. Calcination
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Correct Answer: Option A


Explanation:
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Question #2
Which of the following is the strongest oxidizing agent based on standard reduction potentials?
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Correct Answer: Option A


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Baking powder is a mixture of baking soda and:
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Correct Answer: Option B


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