Skim milk is prepared by the removal of some of the fat from whole milk. This skim milk is found to contain 90.5% water, 3.5% protein, 5.1% carbohydrate, 0.1% fat and 0.8% ash. If the original milk contained 4.5% fat, Calculate its composition assuming that fat only was removed to make the skim milk and that there are no losses in processing.

Fat = 4.5%, Water = 83.5%, protein = 3.0%, carbohydrate = 4.5%, ash = 0.9%

Fat = 4.5%, Water = 86.5%, protein = 3.3%, carbohydrate = 4.9%, ash = 0.8%

Fat = 4.5%, Water = 83.5%, protein = 3.0%, carbohydrate = 4.5%, ash = 0.9%

Fat = 4.6%, Water = 80.5%, protein = 3.5%, carbohydrate = 4.0%, ash = 0.9%

Fat = 4.6%, Water = 81.5%, protein = 3.3%, carbohydrate = 4.5%, ash = 0.8%

7 + Mcqs in Energy Balance Numericals Without Reactions in Bioprocess Engineering Page 1 McqOptions

1.	Refer to Q7, and Express the answer in btu/lb.
A.	0.0421 btu/lb
B.	0.0532 btu/lb
C.	0.0514 btu/lb
D.	0.0432 btu/lb
Answer» D. 0.0432 btu/lb

2.	Water is pumped from a storage tank through a tube of 3.0 cm inside diameter at the rate of 0.001 m³ /s. What is the kinetic energy per kg water in the tube?
A.	2.00 J/kg
B.	1.00 J/kg
C.	5.00 J/kg
D.	0.05 J/kg
Answer» C. 5.00 J/kg

3.	Refer to Q4 and estimate the maximum refrigeration load imposed by this freezing installation assuming the fans but not their motors are in the tunnel.
A.	50.5 tons of refrigeration
B.	40.5 tons of refrigeration
C.	44.5 tons of refrigeration
D.	55.5 tons of refrigeration
Answer» D. 55.5 tons of refrigeration

4.	It is desired to freeze 10,000 loaves of bread each weighing 0.75 kg from an initial room temperature of 18 C to a final temperature of -18 C. The bread-freezing operation is to be carried out in an air-blast freezing tunnel. It is found that the fan motors are rated at a total of 80 horsepower and measurements suggest that they are operating at around 90% of their rating, under which conditions their manufacturer s data claims a motor efficiency of 86%. If 1 ton of refrigeration is 3.52 kW, estimate the maximum refrigeration load imposed by this freezing installation assuming that fans and motors are all within the freezing tunnel insulation and the heat-loss rate from the tunnel to the ambient air has been found to be 6.3 kW. Extraction rate from freezing bread (maximum) = 104 kW
A.	46 tons of refrigeration
B.	40 tons of refrigeration
C.	56 tons of refrigeration
D.	50 tons of refrigeration
Answer» B. 40 tons of refrigeration

5.	A textile dryer is found to consume 4 m³ / hr of natural gas with a calorific value of 800 kJ/mole. If the throughput of the dryer is 60 kg of wet cloth per hour, drying it from 55% moisture to 10% moisture, estimate the overall thermal efficiency of the dryer taking into account the latent heat of evaporation only. Assuming the natural gas to be at standard temperature and pressure at which 1 mole occupies 22.4 liters and Latent heat of evaporation = 2257 kJ/K.
A.	40%
B.	50%
C.	58%
D.	48%
Answer» E.

6.	If 35,000kg of whole milk containing 4% fat is to be separated in a 6 hour period into skim milk with 0.45% fat and cream with 45% fat, what are the flow rates of the two output streams from a continuous centrifuge which accomplishes this separation? (Basis 1 hour s flow of whole milk.)
A.	5678 kg/hr
B.	5368 kg/hr
C.	2567 kg/hr
D.	2578 kg/hr
Answer» C. 2567 kg/hr

7.	Skim milk is prepared by the removal of some of the fat from whole milk. This skim milk is found to contain 90.5% water, 3.5% protein, 5.1% carbohydrate, 0.1% fat and 0.8% ash. If the original milk contained 4.5% fat, Calculate its composition assuming that fat only was removed to make the skim milk and that there are no losses in processing.
A.	Fat = 4.5%, Water = 86.5%, protein = 3.3%, carbohydrate = 4.9%, ash = 0.8%
B.	Fat = 4.5%, Water = 83.5%, protein = 3.0%, carbohydrate = 4.5%, ash = 0.9%
C.	Fat = 4.6%, Water = 80.5%, protein = 3.5%, carbohydrate = 4.0%, ash = 0.9%
D.	Fat = 4.6%, Water = 81.5%, protein = 3.3%, carbohydrate = 4.5%, ash = 0.8%
Answer» B. Fat = 4.5%, Water = 83.5%, protein = 3.0%, carbohydrate = 4.5%, ash = 0.9%