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Question 600440
JEE Chemistry · Hard

Chemical and Ionic Equilibrium: Ostwald MCQ

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OstwaldHardQuestion 600440

Question

Ka of a weak acid HA is 4×10⁻⁵. The degree of dissociation in 0.01 M solution is approximately:
  1. A
    2%
  2. B
    6.3%
    Correct
  3. C
    20%
  4. D
    0.63%

Correct answer

6.3%

Explanation

α = √(Ka/C) = √(4×10⁻⁵/0.01) = √(4×10⁻³) = 0.0632 ≈ 6.3%. The approximation α << 1 holds here (marginally).

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