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Multiple choice question for engineering

Set 1

1. Enthalpy of a stream is which function of temperature and pressure?
a) Explicit
b) Implicit
c) Cannot say
d) None of the mentioned

View Answer

Answer: a [Reason:] Enthalpy of a stream is explicit function of temperature and pressure.

2. In a reaction the feed is 10 moles of 0.1 glucose and 0.9 water, and another feed of 5 moles of 0.2 glucose and 0.8 water, what is the total moles of product?
a) 5
b) 10
c) 15
d) 20

View Answer

Answer: c [Reason:] Total moles of products = 10 + 5 = 15.

3. In a reaction the feed is 10 moles of 0.1 glucose and 0.9 water, and another feed of 5 moles of 0.4 glucose and 0.6 water, what is the fraction of glucose in the products?
a) 0.2
b) 0.4
c) 0.6
d) 0.8

View Answer

Answer: a [Reason:] Total moles of products = 10 + 5 = 15, glucose balance: 0.1*10 + 0.4*5 = x*15, => x = 0.2.

4. In a reaction the feed is 10 moles of 0.1 glucose and 0.9 water, and another feed of 5 moles of 0.4 glucose and 0.6 water, what is the fraction of water in the products?
a) 0.2
b) 0.4
c) 0.6
d) 0.8

View Answer

Answer: d [Reason:] Total moles of products = 10 + 5 = 15, water balance: 0.9*10 + 0.6*5 = x*15, => x = 0.8.

5. In a reaction the feed is 5 moles of 0.5 glucose and 0.5 sucrose, and another feed of 15 moles of 0.3 glucose and 0.7 sucrose, what is the fraction of glucose in the products?
a) 0.35
b) 0.45
c) 0.75
d) 0.95

View Answer

Answer: a [Reason:] Glucose balance: 5*0.5 + 15*0.3 = x*20, => x = 0.35.

6. Two feeds, F1 with H = 10 J/mole and F2 with H = 20 J/mole, and product 10 moles with H = 15 J/mole, what is the F1?
a) 5 mole
b) 10 mole
c) 15 mole
d) 20 mole

View Answer

Answer: a [Reason:] Energy balance: 10*F1 + 20*F2 = 10*15, => F1 + F2 = 10, => F1 = 5 mole.

7. Two feeds, F1 with H = 10 J/mole and F2 with H = 25 J/mole, and product 15 moles with H = 15 J/mole, what is the F2?
a) 5 mole
b) 10 mole
c) 15 mole
d) 20 mole

View Answer

Answer: a [Reason:] Energy balance: 10*F1 + 25*F2 = 15*15, => F1 + F2 = 15, => F2 = 5 mole.

8. Two feeds, 10 moles with H = 10 J/mole and 5 with H = 25 J/mole, what is the enthalpy of products?
a) 5 J/mole
b) 10 J/mole
c) 15 J/mole
d) 20 J/mole

View Answer

Answer: c [Reason:] Energy balance: 10*10 + 5*25 = 15*H, => H = 15 J/mole.

9. Two feeds, 15 moles with H = 10 J/mole and 10 with H = 20 J/mole, what is the enthalpy of products?
a) 8 J/mole
b) 12 J/mole
c) 18 J/mole
d) 25 J/mole

View Answer

Answer: c [Reason:] 25*H = 15*10 + 10*20, => H = 18 J/mole.

10. Two feeds, F1 with H = 10 J/mole and 5 moles with H = 20 J/mole, if the mole of products is 10 what is the enthalpy of products?
a) 10 J/mole
b) 15 J/mole
c) 20 J/mole
d) 25 J/mole

View Answer

Answer: b [Reason:] 10*5 + 5*20 = 10*H, => H = 15 J/mole.

11. Three feeds, 10 mole with H = 5 J/mole, 10 mole with H = 15 J/mole and 5 mole with 20 J/mole, what is the enthalpy of the products?
a) 10 J/mole
b) 12 J/mole
c) 15 J/mole
d) 24 J/mole

View Answer

Answer: b [Reason:] 25*H = 10*5 + 10*15 + 5*20, => H = 12 J/mole.

12. Three feeds, 10 mole with H = 25 J/mole, 5 mole with H = 10 J/mole and 15 mole with 20 J/mole, what is the enthalpy of the products?
a) 10 J/mole
b) 12 J/mole
c) 20 J/mole
d) 28 J/mole

View Answer

Answer: c [Reason:] 30*H = 10*25 + 5*10 + 15*20, => H = 20 J/mole.

13. Three feeds, 10 mole with H = 15 J/mole, 20 mole with H = 5 J/mole and F1 with 20 J/mole, if enthalpy of the products is H = 15 J/mole, what is the value of F1?
a) 10 mole
b) 20 mole
c) 30 mole
d) 40 mole

View Answer

Answer: d [Reason:] 10*15 + 20*5 + F1*20 = (30 + F1)*15, => F1 = 40 mole.

14. Two feeds, 10 mole with 5 J/mole and 20 mole with 15 J/mole, product contains two streams, 5 mole with 10 J/mole and P with 25 J/mole, what is the value of P?
a) 10 mole
b) 12 mole
c) 15 mole
d) 18 mole

View Answer

Answer: b [Reason:] 10*5 + 20*15 = 5*10 + P*25, => P = 12 mole.

15. Two feeds, 5 mole with 25 J/mole and F with 5 J/mole, product contains two streams, 5 mole with 10 J/mole and 10 mole with 15 J/mole, what is the value of F?
a) 10 mole
b) 15 mole
c) 20 mole
d) 25 mole

View Answer

Answer: d [Reason:] 5*25 + F*5 = 5*10 + 10*15, => F = 25 mole.

Set 2

1. A reactor is supplied with 6 moles of CO and 3 moles of O2 and produced 4 moles of CO2, what is the extent of reaction?
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: b [Reason:] The reaction is 2CO + O2 -> 2CO2, => Extent of reaction = (4 – 0)/2 = 2.

2. A reactor is supplied with 6 moles of N2 and 9 moles of H2, if 3 moles of NH3 is produced, how many moles of H2 are left at the end?
a) 1.5
b) 3
c) 4.5
d) 6

View Answer

Answer: c [Reason:] The reaction is N2 + 3H2 -> 2NH3, => extent of reaction = (3 – 0)/2 = 1.5, => moles of H2 left = 9 – 1.5*3 = 4.5.

3. A reactor is supplied with 10 moles of CH4 and 10 moles of O2, if the extent of reaction is 3, what are the moles of CO2 produced?
a) 3
b) 6
c) 8
d) 12

View Answer

Answer: a [Reason:] The chemical reaction is CH4 + 2O2 -> CO2 + 2H2O, => moles of CO2 produced = 3*1 = 3.

4. A reactor is supplied with 10 moles of O2 and 10 moles of H2, if the extent of reaction is 5, how many moles of water is produced?
a) 5
b) 10
c) 15
d) 20

View Answer

Answer: b [Reason:] The chemical reaction is 2H2 + O2 -> 2H2O, => moles of H2O produced = 5*2 = 10.

5. A reactor is supplied with 5 moles of KNO3 and some H2SO4, if the extent of reaction is 2, how many moles of H2SO4 were supplied?
a) 1
b) 2
c) 5
d) Cannot be determined

View Answer

Answer: d [Reason:] Since the final moles of H2SO4 are not given, initial moles cannot be determined.

6. A reactor is supplied with a 100 mole feed of composition 46% C3H7O4, 44% O2 and 10% N2, if 50% of the limiting reagent is converted into product, what is the extent of reaction?
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: b [Reason:] The reaction is 4C3H7O4 + 11O2 -> 12CO2 + 14H2O, => limiting reagent is O2, => Extent of reaction = (44*0.5 – 44)/(-11) = 2.

7. A reactor is supplied with a feed of composition 46% C3H7O4, 44% O2 and 10% N2, if 50% of the limiting reagent is converted into product, what is the percentage of O2 in the product?
a) 10
b) 18
c) 38
d) 54

View Answer

Answer: b [Reason:] The reaction is 4C3H7O4 + 11O2 -> 12CO2 + 14H2O, => Limiting reagent is O2. Let 100 moles of feed was supplied, => after the reaction, moles of CO2 = 24, moles of H2O = 28, moles of O2 = 22, moles of C3H7O4 = 38, moles of N2 = 10, => percentage of O2 = 18%.

8. A reactor is supplied with a feed of composition 46% C3H7O4, 44% O2 and 10% N2, if 50% of the limiting reagent is converted into product, what is the percentage of N2 in the product?
a) 8
b) 18
c) 34
d) 46

View Answer

Answer: a [Reason:] The reaction is 4C3H7O4 + 11O2 -> 12CO2 + 14H2O, => Limiting reagent is O2. Let 100 moles of feed was supplied, => after the reaction, moles of CO2 = 24, moles of H2O = 28, moles of O2 = 22, moles of C3H7O4 = 38, moles of N2 = 10, => percentage of N2 = 8%.

9. A reactor is supplied with a feed of composition 46% C3H7O4, 44% O2 and 10% N2, if 50% of the limiting reagent is converted into product, what is the percentage of C3H7O4 in the product?
a) 10
b) 16
c) 31
d) 43

View Answer

Answer: c [Reason:] The reaction is 4C3H7O4 + 11O2 -> 12CO2 + 14H2O, => Limiting reagent is O2. Let 100 moles of feed was supplied, => after the reaction, moles of CO2 = 24, moles of H2O = 28, moles of O2 = 22, moles of C3H7O4 = 38, moles of N2 = 10, => percentage of C3H7O4 = 31%.

10. A reactor is supplied with a feed of composition 46% C3H7O4, 44% O2 and 10% N2, if 50% of the limiting reagent is converted into product, what is the percentage of H2O in the product?
a) 15
b) 23
c) 39
d) 51

View Answer

Answer: b [Reason:] The reaction is 4C3H7O4 + 11O2 -> 12CO2 + 14H2O, => Limiting reagent is O2. Let 100 moles of feed was supplied, => after the reaction, moles of CO2 = 24, moles of H2O = 28, moles of O2 = 22, moles of C3H7O4 = 38, moles of N2 = 10, => percentage of H2O = 23%.

11. A reactor is supplied with two steams with equal flow rates, stream-1 containing 75% SO2, 25% N2 and stream-2 containing pure H2S, if the product has 1200 grams of S, and the ratio of H2S to H2O is 5 and the ratio of SO2 to H2S is 2, what is the rate of streams?
a) 10 mole
b) 20 moles
c) 30 moles
d) 40 moles

View Answer

Answer: c [Reason:] The reaction is 2H2S + SO2 -> 3S + H2O, => extent of reaction, E = (1200/32)/3 = 12.5, Let the rate be F. nSO2p = 2nH2Sp, => 0.75F – E = 2(F – 2E), => 1.25F = 3(12.5), => F = 30 moles.

12. A reactor is supplied with two steams with equal flow rates, stream-1 containing 75% SO2, 25% N2 and stream-2 containing pure H2S, if the product has 1200 grams of S, and the ratio of H2S to H2O is 5 and the ratio of SO2 to H2S is 2, what fraction of limiting reagent is converted into product?
a) 0.21
b) 0.46
c) 0.73
d) 0.83

View Answer

Answer: d [Reason:] The reaction is 2H2S + SO2 -> 3S + H2O, => extent of reaction, E = (1200/32)/3 = 12.5, Let the rate be F. nSO2p = 2nH2Sp, => 0.75F – E = 2(F – 2E), => 1.25F = 3(12.5), => F = 30 moles, => limiting reagent is H2S, => fraction of H2S converted into product = 2E/F = 2(1.25)/3 = 0.83.

13. A reactor is supplied with two steams with equal flow rates, stream-1 containing 75% SO2, 25% N2 and stream-2 containing pure H2S, if the product has 1200 grams of S, and the ratio of H2S to H2O is 5 and the ratio of SO2 to H2S is 2, how many moles of water are produced?
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: a [Reason:] The reaction is 2H2S + SO2 -> 3S + H2O, => extent of reaction, E = (1200/32)/3 = 12.5, Let the rate be F. nSO2p = 2nH2Sp, => 0.75F – E = 2(F – 2E), => 1.25F = 3(12.5), => F = 30 moles. 5nH2Op = nH2Sp, => 5 nH2Op = 30 – 2(12.5) = 5, => nH2Op = 1.

14. A reactor is supplied with two steams with equal flow rates, stream-1 containing 75% SO2, 25% N2 and stream-2 containing pure H2S, if the product has 1200 grams of S, and the ratio of H2S to H2O is 5 and the ratio of SO2 to H2S is 2, what fraction of excess reagent is converted into product?
a) 0.23
b) 0.55
c) 0.74
d) 0.87

View Answer

Answer: b [Reason:] The reaction is 2H2S + SO2 -> 3S + H2O, => extent of reaction, E = (1200/32)/3 = 12.5, Let the rate be F. nSO2p = 2nH2Sp, => 0.75F – E = 2(F – 2E), => 1.25F = 3(12.5), => F = 30 moles. => The excess reagent is SO2, => fraction of SO2 converted into product = E/0.75F = 12.5/(0.75*30) = 0.55.

15. A reactor is supplied with two steams with equal flow rates, stream-1 containing 75% SO2, 25% N2 and stream-2 containing pure H2S, if the product has 1200 grams of S, and the ratio of H2S to H2O is 5 and the ratio of SO2 to H2S is 2, what is percentage of Sulfur in the product?
a) 23%
b) 47%
c) 61%
d) 84%

View Answer

Answer: c [Reason:] The reaction is 2H2S + SO2 -> 3S + H2O, => extent of reaction, E = (1200/32)/3 = 12.5, Let the rate be F. nSO2p = 2nH2Sp, => 0.75F – E = 2(F – 2E), => 1.25F = 3(12.5), => F = 30 moles. => Moles of SO2 = 0.75F – E = 10, moles of H2S = F – 2E = 5, moles of N2 = 7.5, moles of S = 37.5, moles of H2O = 1, => percentage of sulfur = 61%.

Set 3

1. What is the unit of specific gravity?
a) Kg/m3
b) N/m3
c) m/s2
d) Dimensionless

View Answer

Answer: d [Reason:] Specific gravity of a substance is the ratio of density of the substance and density of a reference substance, so it is dimensionless.

2. What is the specific gravity of a substance with density 100 kg/m3 with respect to reference substance of density 100 lb/m3?
a) 1.1
b) 2.2
c) 3.3
d) 4.4

View Answer

Answer: b [Reason:] Density of the substance = 100*2.2 = 220 lb/m3, Specific gravity = (100*2.2)/100 = 2.2.

3. If is necessary to mention the temperature at which specific gravity is calculated, because
a) Mass of the substance changes with temperature
b) Rigidity of the substance changes with temperature
c) Density of the substance changes with temperature
d) None of the mentioned

View Answer

Answer: c [Reason:] Since volume of the substance changes with temperature, which means density of the substance changes with temperature, that’s why it is required to mention temperature at which specific gravity is calculated.

4. What is the specific gravity of a substance with mass 10 kg and volume 2 m3, with respect to the reference density 50 g/m3?
a) 0.1
b) 0.2
c) 0.3
d) 0.4

View Answer

Answer: a [Reason:] Density of the substance = 10/2 = 5 kg/m3, => Specific gravity = 5/50 = 0.1.

5. What is the mass of a cone of radius 1 m and height 3 m having specific gravity 0.1? (Density of water = 1000 kg/m3)
a) 314.16 kg
b) 425.24 kg
c) 136.16 kg
d) 325.24 kg

View Answer

Answer: a [Reason:] Volume of cone = (1/3) π12*3 = 3.1416 m3, density of cone = 0.1*1000 = 100 kg/m3, => mass of cone = 100*3.1416 = 314.16 kg.

6. API gravity is measured in,
a) Gravity meter scale
b) Hydrometer scale
c) Richer scale
d) None of the mentioned

View Answer

Answer: b [Reason:] API gravity is measured in Hydrometer scale.

7. API gravity is necessary in calculation of specific gravity of petroleum products, because
a) Volume of the petroleum products changes with temperature
b) Mass of petroleum products changes with temperature
c) Potential energy of petroleum products changes with temperature
d) None of the mentioned

View Answer

Answer: a [Reason:] Since volume of petroleum products changes significantly with temperature, that means density of petroleum products changes significantly with temperature, so that’s why specific gravity of petroleum products changes with temperature, and that’s why API gravity is required.

8. What is the API gravity of a substance with specific gravity 1?
a) 131.5
b) 141.5
c) 10
d) 50

View Answer

Answer: c [Reason:] API = (141.5/sp.gr) – 131.5 = 141.5/1 – 131.5 = 10.

9. What is the average mass of a substance with specific gravity 10, and its volume varies with time as V = t/500, from t = 2, to t = 0 seconds? (Density of water = 1000 kg/m3)
a) 25
b) 20
c) 40
d) 75

View Answer

Answer: b [Reason:] Density of substance = 10 * 1000 = 10000 kg/m3, => mass of substance = 10000*t/500 = 20t, => average mass = (1/2)∫20t = 5t2 = 5(22 – 02) = 20.

10. Mass of a substance is changing with respect to its volume as m = -v3 + 3v2 -2v, what is the maximum specific gravity of the substance between v = 1 m3 and v = 2 m3? (Density of reference substance = 0.25 kg/m3)
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: a [Reason:] Density of substance D = m/v = -v2 + 3v – 2, => Specific gravity of substance S = D/0.25 = 4(-v2 + 3v – 2), => dS/dv = 4(-2v + 3) = 0, => v = 1.5, => S is maximum at v = 1.5, => maximum specific gravity = 4(-1.52 + 3*1.5 – 2) = 1.

11. What is the specific gravity of 10 Kg of water occupied in 10 m3 with respect to 200 g/m3?
a) 0.2
b) 0.5
c) 1
d) 5

View Answer

Answer: d [Reason:] Specific gravity = (10/10)/0.2 = 5.

12. What is the specific gravity of 5 Kg of water occupied in 10 m3 with respect to 500 g/m3?
a) 0.5
b) 1
c) 2
d) 5

View Answer

Answer: b [Reason:] Specific gravity = (5/10)/0.5 = 1.

13. What is the specific gravity of 10 Kg of water occupied in 5 m3 with respect to 100 g/m3?
a) 1
b) 5
c) 10
d) 20

View Answer

Answer: d [Reason:] Specific gravity = (10/5)/0.1 = 20.

14. What is the specific gravity of O2 at 27oC and 60 Pa with respect to 1 Kg/m3?
a) 0.15
b) 0.28
c) 0.54
d) 0.76

View Answer

Answer: d [Reason:] Specific gravity = (60*32/8.314*300)/1 = 0.76.

15. What is the specific gravity of N2 at 27oC and 6 Pa with respect to 0.1 Kg/m3?
a) 0.16
b) 0.33
c) 0.51
d) 0.89

View Answer

Answer: b [Reason:] Specific gravity = (6*14/8.314*300)/0.1 = 0.33.

Set 4

1. For exothermic reactions, what is the heat of reaction?
a) Positive
b) Negative
c) Zero
d) Cannot Say

View Answer

Answer: b [Reason:] In exothermic reactions, heat leaves the system, so the heat of reaction is negative.

2. For endothermic reactions, what is the heat of reaction?
a) Positive
b) Negative
c) Zero
d) Cannot Say

View Answer

Answer: a [Reason:] In endothermic reactions, heat comes into the system, so the heat of reaction is positive.

3. Enthalpy of reactants is 15 J/Kg and enthalpy of products is 40 J/Kg, what is the heat of reaction?
a) -10 J/Kg
b) 10 J/Kg
c) -25 J/Kg
d) 25 J/Kg

View Answer

Answer: d [Reason:] Heat of reaction = 40 – 15 = 25 J/Kg.

4. Enthalpy of reactants is 50 J/Kg and enthalpy of products is 25 J/Kg, what is the heat of reaction?
a) -10 J/Kg
b) 10 J/Kg
c) -25 J/Kg
d) 25 J/Kg

View Answer

Answer: c [Reason:] Heat of reaction = 25 – 50 = -25 J/Kg.

5. Enthalpy of reactants is 30 J/Kg and enthalpy of products is 10 J/Kg, what is the heat of reaction?
a) -20 J/Kg
b) 20 J/Kg
c) -10 J/Kg
d) 10 J/Kg

View Answer

Answer: a [Reason:] Heat of reaction = 10 – 30 = -20 J/Kg.

6. Heat of formations of A, B, C, and D, are 5 J, 10 J, 15 J, and 20 J respectively, what is the heat of reaction A + 4B -> 3C + D?
a) 10 J
b) 20 J
c) 35 J
d) 45 J

View Answer

Answer: b [Reason:] Heat of reaction = 20 + 3*15 – 4*10 – 5 = 20 J.

7. Heat of formations of A, B, C, and D, are 5 J, 8 J, 2 J, and 15 J respectively, what is the heat of reaction 3A + B -> 3C + 2D?
a) 9 J
b) 10 J
c) 13 J
d) 15 J

View Answer

Answer: c [Reason:] Heat of reaction = 2*15 + 3*2 – 8 – 3*5 = 13 J.

8. Heat of formations of A, B, C, and D, are 1 J, 2 J, 3 J, and 4 J respectively, what is the heat of reaction 3A + 4B -> 2C + D?
a) -1 J
b) 1 J
c) 3 J
d) 6 J

View Answer

Answer: a [Reason:] Heat of reaction = 4 + 2*3 – 4*2 – 3*1 = -1 J.

9. Heat of formations of A, B, C, and D, are 2 J, 5 J, 3 J, and 10 J respectively, what is the heat of reaction 4A + 5B -> 2C + 2D?
a) -10 J
b) -7 J
c) -5 J
d) 0

View Answer

Answer: b [Reason:] Heat of reaction = 2*10 + 2*3 – 5*5 – 4*2 = -7 J.

10. Heat of formations of A, B, C, and D, are 3 J, 5 J, 4 J, and 8 J respectively, what is the heat of reaction 2A + 2B -> 2C + D?
a) -5 J
b) 0
c) 5 J
d) 8 J

View Answer

Answer: b [Reason:] Heat of reaction = 8 + 2*4 – 2*5 – 2*3 = 0.

11. In the reaction C + O2 -> CO2, if the heat liberated is 10 J, what is the heat of formation of CO2?
a) -10 J
b) 10 J
c) 0
d) Cannot be determined

View Answer

Answer: a [Reason:] Heat of formation = -10 J.

12. In the reaction 2H2 + O2 -> 2H2O, if the heat liberated is 50 J, what is the heat of formation of H2O?
a) -25 J
b) 25 J
c) -50 J
d) 50 J

View Answer

Answer: a [Reason:] Heat of formation = -50/2 = -25 J.

13. In the reaction 2N -> N2, if the heat liberated is 6 J, what is the heat of formation of N2?
a) – 6 J
b) 6 J
c) 0
d) Cannot be determined

View Answer

Answer: a [Reason:] Heat of formation = -6 J.

14. In the reaction 2C + O2-> 2CO, if the heat liberated is 10 J, what is the heat of formation of CO?
a) -5 J
b) 5 J
c) -10 J
d) 10 J

View Answer

Answer: a [Reason:] Heat of formation = -10/2 = -5 J.

15. In the reaction C + 2H2 -> CH4, if the heat liberated is -5 J, what is the heat of formation of CH4?
a) -5J
b) 5 J
c) 0 J
d) Cannot be determined

View Answer

Answer: b [Reason:] Heat of formation = – (-5) = 5 J.

Set 5

1. Which of the following remains constant in steady state system?
a) Mass
b) Energy
c) Momentum
d) Density

View Answer

Answer: a [Reason:] In a steady state system what amount of material goes in same amount comes out, so the overall mass remains constant.

2. A reaction occurs in a vessel such that its mass does not change but its temperature is increased, then the system is which of the following?
a) Steady-state
b) Unsteady-state
c) Cannot say
d) None of the mentioned

View Answer

Answer: b [Reason:] For a steady-state system all the properties temperature, pressure, mass should remain constant with respect to time, so it is an unsteady-state process.

3. A fluid enters a vessel at the rate of 10 liters/s, and leaves in two pathways one with 7 liters/s and other with 3 liters/s, then what type of flow it is?
a) Steady-state
b) Unsteady-state
c) Cannot say
d) None of the mentioned

View Answer

Answer: a [Reason:] Since the flow in rate and flow out rate of the fluid are equal, the system is in steady-state.

4. A fluid enters a vessel at the rate of 10 liters/s, and leaves in two pathways one with 5 liters/s and other with 3 liters/s, then what type of flow it is?
a) Steady-state
b) Unsteady-state
c) Cannot say
d) None of the mentioned

View Answer

Answer: b [Reason:] Since the flow in rate and flow out rate of the fluid are unequal, the system is in unsteady-state.

5. The rate flow in and flow out in an unsteady state process are now increased by 10 Kg/s, which will be the change in accumulation?
a) 0
b) 5 Kg/s
c) 10 Kg/s
d) 20 Kg/s

View Answer

Answer: a [Reason:] Initial accumulation = rate of flow out – rate of flow in, => Final accumulation = (rate of flow out + 10) – (rate of flow in + 10) = Initial accumulation, => Change in accumulation = 0.

6. An unsteady-state system, with 10 liters as initial amount of water in the vessel, water flow in rate is 8 liters/ s and flow out rate is 5 liters/s, what will be the amount of water in the vessel after 10 seconds?
a) 10 liters
b) 20 liters
c) 30 liters
d) 40 liters

View Answer

Answer: d [Reason:] Amount of water added to the vessel in 10 seconds = (8 – 5)*10 = 30 liters, => Final amount of water = 10 + 30 = 40 liters.

7. An unsteady-state system, with 6 liters as initial amount of water in the vessel, water flow in rate is 2 liters/ s and flow out rate is 4 liters/s, what will be the amount of water in the vessel after 1 seconds?
a) 2 liters
b) 4 liters
c) 6 liters
d) 8 liters

View Answer

Answer: b [Reason:] Total amount of water reduced from the vessel in 1 second = (4 – 2)*1 = 2 liters, => Final amount of water = 6 – 2 = 4 liters.

8. What is the final amount of fluid in the vessel if the system is in steady state?
a) Same as the initial amount
b) Twice the initial amount
c) Zero
d) None of the mentioned

View Answer

Answer: a [Reason:] Since in steady-state the rate of flow in is equal to rate of flow out, so final amount of fluid in the vessel is same as the initial amount.

9. In what ratio 57 octane and 63 octane should be mixed to obtain 59 octane?
a) 1:1
b) 2:1
c) 3:1
d) 4:1

View Answer

Answer: b [Reason:] 59*1 = 63*x + 57*(1 – x), => x= 1/3, => 1 – x = 2/3, => ratio of 57 octane: 63 octane = 2/3:1/3 = 2:1.

10. What amount of 57 octane should be mixed with 3 liters of 63 octane to obtain 4 liters of 59 octane?
a) 1 liter
b) 2 liters
c) 2.5 liters
d) 4.5 liters

View Answer

Answer: d [Reason:] 59*1 = 63*x + 57*(1 – x), => x = 1/3, now 4 = (1/3)*3 + (2/3)*w, => w = 4.5 liters.

11. An unsteady state system, the flow in rate of A is 10 mole/s, what is the flow out rate of B if the accumulation was 10 mole in 2 seconds?
a) 5 mole/s
b) 10 mole/s
c) 15 mole/s
d) 20 mole/s

View Answer

Answer: a [Reason:] Flow rate of B = 10 – 10/2 = 5 mole/s.

12. An unsteady state system, the flow in rate of A is 12 mole/s, what is the flow out rate of B if the accumulation was 18 mole in 3 seconds?
a) 4 mole/s
b) 6 mole/s
c) 8 mole/s
d) 9 mole/s

View Answer

Answer: b [Reason:] Flow rate of B = 12 – 18/3 = 6 mole/s.

13. An unsteady state system, the flow in rate of A is 5 mole/s, what is the flow out rate of B if the accumulation was 10 mole in 5 seconds?
a) 1 mole/s
b) 2 mole/s
c) 3 mole/s
d) 5 mole/s

View Answer

Answer: c [Reason:] Flow rate of B = 5 – 10/5 = 3 mole/s.

14. An unsteady state system, the flow in rate of A is 8 mole/s, what is the flow out rate of B if the accumulation was 6 mole in 2 seconds?
a) 1 mole/s
b) 2 mole/s
c) 3 mole/s
d) 5 mole/s

View Answer

Answer: d [Reason:] Flow rate of B = 8 – 6/2 = 5 mole/s.

15. An unsteady state system, the flow in rate of A is 6 mole/s, what is the flow out rate of B if the accumulation was 18 mole in 9 seconds?
a) 1 mole/s
b) 2 mole/s
c) 3 mole/s
d) 4 mole/s

View Answer

Answer: d [Reason:] Flow rate of B = 6 – 18/9 = 4 mole/s.