This set of Engineering Materials & Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Copper and its Alloys – 1”.
1. How much copper is present in deoxidized copper?
a) > 99.9%
b) > 99.85%
c) > 99.5%
d) > 99.35%
Explanation: Deoxidized copper contains over 99.85% Cu, along with As, Fe, and Bi. It is mainly used to remove cuprous oxides and reduce porosity. Arsenic deoxidized copper and arsenic touch pitch copper contain over 99.5% and 99.35% copper respectively.
2. High conductivity copper is used ______
a) In electrical engineering
b) To reduce porosity
c) To raise softening temperature
d) To manufacture semiconductor elements
Explanation: High conductivity copper contains over 99.9% copper, less than 0.005% of both lead and iron, along with low oxygen content. This copper finds its applications in the field of electrical engineering as it is a great conductor of electricity.
3. Which copper grade is used to manufacture semiconductors and particle accelerator components?
a) High conductivity copper
b) Deoxidised copper
c) Oxygen-free copper
d) Arsenic deoxidized copper
Explanation: Semiconductor and superconductor components require high chemical purity. Oxygen-free copper serves this purpose, as well as for high vacuum devices like particle accelerators. This copper is valued for its purity, rather than its electrical conductivity.
4. What is the melting point of Copper?
Explanation: Copper is a soft and ductile material with good electrical and thermal conductivities. It’s melting point is 1084 and the boiling point is 2562.
5. Brass is an alloy of copper and ______
c) Tin and zinc
Explanation: Brasses are alloys which are stronger than plain copper. They are primarily composed of copper and zinc, and may additionally contain tin, lead, aluminum etc. They can be used to cast molds, draw wires, roll sheets, and turned into tubes.
6. α brasses contain ______ of zinc.
Explanation: Brasses are classified into two types depending on the amount of zinc contained in them. Brasses up to 36% zinc are known as brasses. They are relatively soft, ductile, and are easily cold worked. On the other hand, brasses with over 36% zinc are available in two different phases; they are stronger than brasses.
7. What is the appearance of copper?
Explanation: Pure copper generally appears in a reddish-orange color. It is a metal with a lustrous property. Brass, an alloy of copper, may appear red or white, depending on the amount of zinc.
8. Addition of tellurium to copper results in ________
a) High strength
b) Decreased electrical conductivity
c) Increased machinability
d) No effect
Explanation: When copper is added with tellurium, it gives good machinability. Beryllium, chromium, or 1-3% lead can be added to increase strength. Cadmium also increases strength but reduces electrical conductivity.
9. _______ is an alloy of copper and tin.
Explanation: Bronze is a high strength an alloy made of copper and tin. It has a better corrosion resistance compared to brasses.
10. Yellow metal is more commonly known as ______
a) Cartridge brass
b) Naval brass
c) Admiralty brass
d) Muntz metal
Explanation: Muntz metal is a brass alloy, which is otherwise also known as yellow metal. It consists of 60% copper and 40% zinc. They are commonly used for extruding rods and tubes, and for making condenser or heat exchanger plates.
11. Which brass alloy has high tensile strength and can be used for cast molding?
a) Manganese brass
b) Free cutting brass
c) Standard brass
d) Gilding metal
Explanation: Manganese brass has a good tensile strength compared to other brass alloys. It is also known as high tensile brass. They can be hot worked, and are commonly used for making pump-rods, and marine castings.
12. Which brass alloy is used to make imitation jewelry and decorative work?
a) Standard brass
b) Admiralty brass
c) Free cutting brass
d) Gilding metal
Explanation: Gilding metal, which is also known as commercial metal, is used for making coins, medals, artificial jewelry, and decorative work. It consists of 90% copper and 10% zinc. It is gold in appearance and had a good ductility.
13. Which brass alloy is suitable for high-speed machining?
a) Gilding metal
b) High tensile brass
c) Leaded brass
d) Muntz metal
Explanation: Leaded brass is used for high-speed machining due to its excellent strength and heat resistance. It contains 59% Cu, 39% Zn, and 2% Pb. It is also known as free cutting brass.
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