Material Science MCQ Set 9

MATERIAL SCIENCE MCQ SET 9

Q1. The process of introducing nitrogen into steel surfaces is called:

A) Carburization
B) Nitriding
C) Tempering
D) Normalizing

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Answer: B) Nitriding
Explanation: Nitrogen forms hard nitrides, improving surface hardness and wear resistance.

Q2. Stainless steel is classified based on:

A) Carbon content
B) Chromium and nickel content
C) Iron content only
D) Manganese content

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Answer: B) Chromium and nickel content
Explanation: Austenitic, ferritic, and martensitic stainless steels differ mainly by Cr and Ni content.

Q3. Which of the following metals has FCC crystal structure?

A) Iron (room temp)
B) Aluminum
C) Zinc
D) Magnesium

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Answer: B) Aluminum
Explanation: Aluminum has FCC structure, giving high ductility and formability.

Q4. The main constituent of tool steel is:

A) Carbon and tungsten
B) Copper and tin
C) Iron and aluminum
D) Nickel and chromium

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Answer: A) Carbon and tungsten
Explanation: Tool steels are high-carbon steels often alloyed with tungsten for hardness and wear resistance.

Q5. Which of the following is brittle at room temperature?

A) Copper
B) Aluminum
C) Ceramics
D) Mild steel

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Answer: C) Ceramics
Explanation: Ceramics have low tensile strength and fail suddenly under stress.

Q6. The main alloying element in bronze is:

A) Zinc
B) Tin
C) Aluminum
D) Nickel

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Answer: B) Tin
Explanation: Bronze is a copper-tin alloy with good corrosion resistance and wear properties.

Q7. Martensite transforms to tempered martensite by:

A) Rapid quenching
B) Slow cooling
C) Heating to a moderate temperature
D) Cold working

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Answer: C) Heating to a moderate temperature
Explanation: Tempering relieves stresses and improves toughness of martensite.

Q8. Polymers that can be remolded after heating are called:

A) Thermosetting
B) Thermoplastic
C) Elastomers
D) Ceramics

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Answer: B) Thermoplastic
Explanation: Thermoplastics soften on heating and harden on cooling, allowing reshaping.

Q9. The main advantage of aluminum alloys in aerospace is:

A) High density
B) Low strength
C) Lightweight and corrosion resistance
D) High thermal expansion

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Answer: C) Lightweight and corrosion resistance
Explanation: Low density and good mechanical properties make aluminum alloys ideal for aircraft.

Q10. Which metal has a BCC structure at room temperature?

A) Aluminum
B) Iron
C) Copper
D) Zinc

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Answer: B) Iron
Explanation: Alpha iron (ferrite) has a BCC structure at room temperature.