Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : In titratable acidity determination of milk by titration method, the pink colour (phenolphthalein end point) disappears soon, whereas in normal acid-base titration, it persists for long time.
Reason (R) : Due to alkalinity of the medium after the titration, there is a shift in the equilibrium of milk salts releasing more of hydrogen ions.
In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

To minimize this fading effect and obtain a stable, accurate endpoint:
Add a small amount of neutral potassium oxalate to the milk sample before titration.
This precipitates the soluble calcium as calcium oxalate, preventing the formation of tricalcium phosphate and stabilizing the pink endpoint.

Answer 1

The Correct Option is A