Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Care should be taken to test only fresh samples of milk for freezing point depression, as aged samples can actually depress the freezing point such that the presence of extraneous water could be masked.
Reason (R) : The production of four molecules of lactic acid from one molecule of lactose during storage of milk increases freezing point depression.
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:

For accurate cryoscopic testing, always check the titratable acidity of the milk sample first.
If the titratable acidity exceeds $0.18\%$ (expressed as lactic acid), the milk is starting to sour, and the measured freezing point will be artificially low, making it invalid for detecting added water.

Answer 1

The Correct Option is A