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An alkali is titrated against an acid with methyl orange as indicator, which of the following is a correct combination?

Options

  1. ABase Acid End point Strong Strong Pink to colourless
  2. BBase Acid End point Weak Strong Colourless to pink
  3. CBase Acid End point Strong Strong Pinkish red to yellow
  4. DBase Acid End point Weak Strong Yellow to pinkish red

Correct answer

D. Base Acid End point Weak Strong Yellow to pinkish red

Step-by-step solution

Methyl orange is weak organic base. It is used in the titration of weak base vs strong acid. M e O H Unionized form ( Yellow ) ⇌ M e + + O H - Ionized form ( Red ) In basic medium, equilibrium lies in backward direction and therefore it shows yellow colour. In acidic medium, equilibrium shifts in forward direction and therefore, colour changes from yellow to red.

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