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JEE Main2007ChemistryIonic EquilibriumActual

The pKa of a weak acid ( HA ) is 4.5 . The pOH of an aqueous buffered solution of HA in which 50 % of the acid is ionized is

Options

  1. A4.5
  2. B2.5
  3. C9.5
  4. D7.0

Correct answer

C. 9.5

Step-by-step solution

For buffer solution aligned & pH = pK _ a + [ Salt ] [ Acid ] & =4.5+ [ Salt ] [ Acid ] aligned as HA is 50 % ionized so [ Salt ] = [ Acid ] aligned & pH =4.5 & pH + pOH =14 & pOH =14-4.5=9.5 aligned Hence (C) is correct.

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