Question

Which of the following statements are CORRECT? 

• A. P and Q only
• B. Q and R only
• C. R and S only
• D. P and S only

Hint:

Rheopectic and dilatant fluids exhibit an increase in viscosity with time or deformation rate, while pseudoplastic fluids show a decrease in viscosity with increasing shear stress.

Answer 1

The Correct Option is D

- P is correct: Rheopectic fluids increase in apparent viscosity with time under constant shear stress. 
- Q is incorrect: For pseudoplastic fluids, the apparent viscosity decreases with increasing shear stress, not time.
- R is incorrect: For Bingham plastics, the apparent viscosity does not increase exponentially with deformation rate; it is a constant above the yield stress. 
- S is correct: For dilatant fluids, the apparent viscosity increases with increasing deformation rate. 
Conclusion: P and S are correct, so the correct answer is (D).