1. Air blasts are provided for forced cooling of sand after muller operation.
a) True
b) False
Explanation: Mullers usually need approximately 33 to 50 percent of mulling time. In a high speed sand preparation unit, after the muller operation is complete, to cool the sand, air blasts are used.
2. High moisture causes what in molding sands?
a) Increase in permeability
b) Decrease in permeability
c) Increase in hardness
d) Increase in strength
Explanation: Permeability is basically the magnitude of pores present in the sands and its capacity of moisture it can hold. High moisture content causes a decrease in permeability of the sand and hence causes other problems in it.
3. The pressure of which gas gives the reading of water content on the pressure gauge?
a) Methane
b) Acetone
c) Acetylene
d) Carbon dioxide
Explanation: Methane, carbon dioxide and acetone are not very useful when it comes to take readings on the pressure gauge. Acetylene gas helps in getting a direct reading on the pressure gauge of the water content.
4. Calcium carbide reacts with moisture to give out which gas?
a) Acetylene gas
b) Methane
c) Carbon dioxide
d) Carbon monoxide
Explanation: According to the chemical reaction, Calcium carbide when reacts with moisture, that is water, it is observed to give out calcium hydroxide and acetylene gas.
5. In a moisture content test, what amount of prepared sand is placed on the pan?
a) 10-40 grams
b) 20-50 grams
c) 30-60 grams
d) 40-70 grams
Explanation: When the tests for composition present in the pan are taken, sands are a very important factor in it. In a moisture content test, approximately 20 grams to 50 grams of prepared sand is taken in the pan.
6. In a moisture content test, how is the prepared sand heated?
a) Flame heating
b) Ultraviolet heating
c) Infrared heating
d) Conduction heating
Explanation: In a moisture content test, the prepared sand is taken in a pan, about 20 to 50 grams, and then heated using infrared heating.
7. In a moisture content test, for how long should the sand in infrared heating bulb be heated?
a) 1 – 2 minutes
b) 2 – 3 minutes
c) 3 – 4 minutes
d) 4 – 5 minutes
Explanation: The moisture content tests are highly performed in a heating bulb. About 20 to 50 grams of the prepared sand is heated using infrared heating for 2 to 3 minutes in the infrared heating bulb.
8.In clay content determination of molding sand, which is the base solution used?
a) KOH
b) NaOH
c) Mg(OH)2
d) Ca(OH)2
Explanation: For knowing the exact details of the compositions present in the sand, various tests have to be performed. In clay content determination of the molding sand, 3% sodium hydroxide (NaOH) is used.
9. How much distilled water is added to 3% NaOH solution in clay content determination of molding sand?
a) 450 cc
b) 475 cc
c) 500 cc
d) 550 cc
Explanation: A strong base is used in the clay content determination, like sodium hydroxide. 475 cc of distilled water is added to 3% NaOH solution on the determination of clay content of molding sands.
10. Grain distribution is not determined by the Grain fineness test.
a) True
b) False
Explanation: For knowing the exact details of the compositions present in the sand, various tests have to be performed, one of them is grain fitness test. Grain fineness test determines the grain size, grain distribution and grain fineness.