Practice Exams ChE - 28

1. A 300 cu. ft. reactor, initially full of air needs to be purged of its O2 content. N2, containing 15% O2 is blown into the reaction while an equivalent amount is purged. If the concentration of the O2 must be brought to less than 1% in 24 hours, at what rate must the N2 enter the reactor?
a. 78.2
b. 40
c. 23.4
d. 6.9
e. none of these

2. A berl saddle is used
a. so that one can easily ride a horse
b. to resolve a personal problem
c. to increase mass transfer rate
d. to increase heat transfer rate
e. none of these

3. Secondary air pollutants, also called photochemical smog, are the result of the synergestic reaction of primary air pollutants in the presence of UV radiation. Which of the following is not a photochemical smog?
a. peroxy acetylnitrate
b. benzopyrene
c. aldehydes
d. hydrocarbons
e. none of these

4. XF = 0.45
XP = 0.65
XR = 0.75
P = 8.33 tons/hr

The effectiveness of the screen is:
a. 60.8%
b. 55.6%
c. 52.8%
d. 62.8%
e. none of these

5. The orifice coefficient Co is always determined experimentally. If NRe at the orifice is above 30,000 and the ratio of the orifice diameter to the diameter of the conduit is less than about ___, the value of Co is approximately 0.61
a. ½
b. ¾
c. 1
d. ¼
e. none of these

6. A block of wood floats in water with 6 inches projecting above the water surface. If the same block were placed in alcohol of specific gravity of 0.82, the block would project 4 inches above the surface of the alcohol. The specific gravity of the wood block is
a. 0.8
b. 0.9
c. 0.6
d. 0.7
e. none of these

7. The increase in the power requirement of a centrifugal pump when the speed is increased by 20% is approximately
a. 100%
b. 73%
c. 44%
d. 14.5%
e. none of these

8. What would be the thickness required of a welded cone head with maximum inside diameter of 48 inches, half an apex angle of 30ยบ, double-welded butt joints with no radiography employed, P = 500 psi and S=12,500 lb/sq. in.?
a. 1.16 in
b. 1.12 in
c. 1.5 in
d. 0.98 in
e. none of these

9. The adsorbent used in the purification of hydrocarbon products is
a. alumina
b. bone char
c. fuller’s earth
d. silica gel
e. none of these

10. 90% of the NH3 entering an NH3-oxidation unit is converted to HNO3 and 10% NH3 is due to conversion losses, NO in the stack gases & miscellaneous losses. The kg of NH3 necessary to produce 60000 kg of 62 wt % NH3 is:
a. 11 150
b. 12 000
c. 12 150
d. 11 000
e. none of these


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