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At 25 o C , p H range of phenolphthalein is 8 - 10 . At 100 o C , pH range of phenolphthalein would be -

Options

  1. ApH range remain unaffected by the temperature
  2. BpH range is altered to 7 - 9
  3. CpH range is altered to 7 - 11
  4. DpH range is altered to 8 - 11

Correct answer

B. pH range is altered to 7 - 9

Step-by-step solution

The pH range of the indicator is p K I n ± 1 . On increase in temperature p K I n decreases therefore pH range of indicator decreases.

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