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GATE 2025 BT – Question 25

Fundamentals of Biological Engineering · Bioreaction Engineering: Batch, fed-batch and continuous processes, microbial and enzyme reactors, optimization and scale up · 1 mark · Multiple select

Which of the following fluids exhibit(s) non-Newtonian behaviour at 25 $^o$C?

  1. Toothpaste
  2. Mercury
  3. Brine
  4. Blood plasma

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Show answer and explanation

Correct answer: (A) Toothpaste

Explanation

Toothpaste is a Bingham plastic, with a yield stress. Mercury, brine and blood plasma are Newtonian liquids. (Whole blood, with its cells, is non-Newtonian, but plasma is not.)