250+ TOP MCQs on Raw Materials for Foundry and Answers

Foundry Multiple Choice Questions on “Raw Materials for Foundry”.

1. Ore is _________ to make it suitable for foundry processes.
a) Smelted
b) Melted
c) Extracted
d) Refined
Answer: a
Clarification: Smelting is form of extractive metallurgical process which is responsible for the extraction of various metals from the ores that are available in the earth’s crust. Hence, the ores are smelted to make them feasible to use in the foundry processes.

2. The metals that are used in foundries are obtained in which of the following sources?
a) Oxides
b) Sulphides
c) Carbonates
d) Aldehydes
Answer: d
Clarification: The aldehyde is an organic compound which contains a functional group which has the structure of –CHO group. They are formed by oxidation of alcohol which is not available in the crust. As it is in liquid form it is chemically prepared and is not available in the crust.

3. Anthracite coal is used to melt the metals in foundry.
a) True
b) False
Answer: a
Clarification: Anthracite coal is the best type of coal among the other type of coals. The anthracite coal has the least amount of impurities and it releases less amount of pollution and more energy and hence it is used in foundries.

4. The source of energy that keeps the furnace the cleanest is __________
a) Electricity
b) Water
c) Air
d) Sunlight
Answer: a
Clarification: In a foundry, electricity is the easiest and the most expensive source of energy available. When the furnaces are electrically powered, there is no amount of smoke found and the particulate matter does not settle down. Hence, it keeps the furnaces clean.

5. Charcoal is the prime material used in copper-alloy foundry.
a) True
b) False
Answer: a
Clarification: In copper-alloy foundry practice, charcoal is used to prevent the molten metal from being oxidized, and some commercially available fluxes may be employed to cleanse the metal that is to separate it from dross. Hence it is a prime material in the copper-alloy foundry.

6. The flux used in the foundries to make castings of magnesium alloys are ________
a) Potassium Chloride
b) Barium Chloride
c) Magnesium Oxide
d) Potassium Chloride, Barium Chloride and Magnesium Oxide
Answer: d
Clarification: The fluxes are used for melting magnesium alloys prevent the burning of magnesium alloys. The fluxes listed above have excellent properties as fluxes in foundries. Nitrogen (gaseous flux) is used to bubble slowly through the molten magnesium for removing hydrogen.

7. The melting point of the flux is _________
a) Low
b) High
c) Room Temperature
d) Critical
Answer: a
Clarification: The flux, when heated up, melts and combines with the ash, viscous slag, sand, metallic oxides etc., and make a flowing slag. To form the slag, it is important for the flux to be composed of the low melting point.

8. _____________ protects molten metal from atmosphere in the foundry.
a) Pattern
b) Mould
c) Slag
d) Refractories
Answer: c
Clarification: The slag being the lighter part comes on to the surface of the molten metal from where it can be easily skimmed, tapped or removed before pouring the metal into the mould. Hence, the slag does not allow the metal to be in contact with the atmosphere.

9. In the foundry, the electric furnaces cannot operate for high temperatures.
a) True
b) False
Answer: b
Clarification: The electric furnaces usually operate up to high temperatures of 1700^oC. As the electric induction and electric resistance furnaces are used to melt almost all types of metals, it is seen that electric furnaces operate at a wide range of temperatures.

10. Limestone removes sulphur from cast iron.
a) True
b) False
Answer: a
Clarification: Limestone is chemically known as sodium carbonate. It is used in cupola while melting cast iron. It gives rise to a slag which removes sulphur from cast iron in foundry processes.