Which of the following statements are not correct?
a) Antihistamine also functions as an antacid
b) The shape of an active site of an enzyme does not change when the drug binds to an allosteric site
c) Chemical messengers communicate the message between two neurons
d) Potassium soaps are hard, while sodium soaps are soft to skin
The correct answer is

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.