#### An alkali is titrated against an acid with methyl orange as indicator, which of the following is a correct combination? Option 1) Base             Acid             End Point Strong          Strong          Pink to colourless    Option 2) Base             Acid             End Point Weak            Strong          Colourless to pink Option 3) Base             Acid             End Point Strong          Strong          Pinkish red to yellow Option 4) Base             Acid             End Point Weak            Strong          Yellow to pinkish red

As we learned

Value of p(H) -

Acidic solution has p(H)  < 7

Basic solution has  p(H)  > 7

Neutral solution has p(H) = 7

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Methyl orange changes its colour in acidic medium when pH is around 3 to 5 and its colour is yellow in basic medium and red in acidic medium so it is used in titration of weak base with strong acid.

Option 1)

Base             Acid             End Point

Strong          Strong          Pink to colourless

Option 2)

Base             Acid             End Point

Weak            Strong          Colourless to pink

Option 3)

Base             Acid             End Point

Strong          Strong          Pinkish red to yellow

Option 4)

Base             Acid             End Point

Weak            Strong          Yellow to pinkish red