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

An alkali is titrated against acid with methyl orange as an indicator, which of the following is a correct combination?
  1. BaseAcidEnd pointStrongStrongPink to colourless
  2. BaseAcidEnd pointWeakSrtongColourless to pink
  3. BaseAcidEnd pointStrongstrongPinkish red to yellow
  4. BaseAcidEnd pointWeakStrongYellow to pinkish red

Solution

The pH range between 3.1 (red) and 4.4 (yellow) is the colour-change interval of methyl orange.

Weak base has pH > 7. So, when methyl orange indicator is added the solution turns yellow & if the solution is titrated against strong acid it turns pinkish red at the end point i.e., pH <3.1.

Asked in: JEE Main 2018 (08 Apr)

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