# Downstream Processing – Section 1

26. For the extractions operation, the selectivity should be

A. > 1
B. < 1
C. 1
D. zero

27. The purity of a solute collected between two times t1 and t2 during chromatographic separation can be calculated as

A. amount of solute eluted – amount of impurity eluted
B. amount of solute eluted / amount of impurity eluted
C. amount of solvent eluted + amount of impurity eluted
D. amount of solvent eluted / amount of impurity eluted

Correct Answer: B. amount of solute eluted / amount of impurity eluted

28. Chromatography is based on the

A. different rate of movement of the solute in the column
B. separation of one solute from other constituents by being captured on the adsorbent
C. different rate of movement of the solvent in the column
D. any of the above

Correct Answer: A. different rate of movement of the solute in the column

29. The correlation often employed to correlate adsorption data for protein is (where Ymax is the maximum amount of solute adsorbed per mass of adsorbent, X is the mass fraction of solute in the diluent phase in solute-free basis, KL is a constant and Y is the equilibrium value of the mass of solute adsorbed per mass of adsorbent)

A. Y = YmaxX/(KL+X)
B. Y = Ymax/(KL+X)
C. Y = YmaxX/KL
D. Y = YmaxX/ (KL+X)

Correct Answer: A. Y = YmaxX/(KL+X)

30. A typical tubular centrifuge has a bowl of 2 to 5 inch in diameter and 9 to 30 inch in height with a maximum rotating speed of

A. 15,000 to 50,000 rpm
B. 50,000 to 100,000 rpm
C. 100,000 to 150,000 rpm
D. 150,000 to 200,000 rpm

Correct Answer: A. 15,000 to 50,000 rpm