11. In the submerged process for the fermentation to produce citric acid,

A. A. niger is used with the solid substrate as sweet potato
B. A. niger floats on the surface of the solution
C. Fungal mycelium grows throughout the solution in a deep tank
D. both (a) and (b)

12. Which substrate is used in the fermentation of citric acid?

A. Beet molasses
B. Sucrose
C. Starch hydrolysate
D. All of these

13. Alegar is a type of vinegar produced from

A. fruit juices
B. malted grain
C. ethanol
D. ale

14. During the recovery step of citric acid, calcium citrate formed is treated with which of the following acid to precipitate calcium?

A. HCl
B. HNO₃
C. H₂SO₄
D. None of these

15. Vinegar production consists of

A. aerobic fermentation
B. anaerobic fermentation
C. aerobic fermentation followed by anaerobic fermentation
D. anaerobic fermentation followed by aerobic fermentation