Material Science MCQ Set 6

MATERIAL SCIENCE MCQ SET 6

Q1. The hardness of steel can be increased by:

A) Annealing
B) Normalizing
C) Quenching
D) Softening

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Answer: C) Quenching
Explanation: Rapid cooling forms martensite, a hard and brittle phase, increasing hardness.

Q2. Which metal has a hexagonal close-packed (HCP) structure?

A) Iron (at room temperature)
B) Copper
C) Zinc
D) Aluminum

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Answer: C) Zinc
Explanation: Zinc crystallizes in HCP structure, limiting slip systems and reducing ductility.

Q3. The material most suitable for electrical insulation is:

A) Copper
B) Aluminum
C) Ceramic
D) Steel

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Answer: C) Ceramic
Explanation: Ceramics are excellent insulators due to high resistivity and low free electrons.

Q4. Which of the following is a quaternary alloy?

A) Brass
B) Steel
C) Stainless steel
D) Inconel

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Answer: D) Inconel
Explanation: Inconel contains nickel, chromium, iron, and other elements; hence, quaternary.

Q5. The main constituent of gray cast iron is:

A) Pearlite
B) Ferrite
C) Graphite
D) Cementite

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Answer: C) Graphite
Explanation: Gray cast iron has flake graphite in a pearlitic or ferritic matrix, giving good damping properties.

Q6. Which test measures a material’s resistance to indentation?

A) Tensile test
B) Hardness test
C) Impact test
D) Fatigue test

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Answer: B) Hardness test
Explanation: Rockwell, Brinell, and Vickers tests measure hardness by indentation depth or size.

Q7. Which phase in steel is soft and ductile?

A) Ferrite
B) Cementite
C) Martensite
D) Bainite

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Answer: A) Ferrite
Explanation: Ferrite (α-Fe) is soft, ductile, and magnetic at room temperature.

Q8. Bainite offers:

A) Maximum hardness
B) Maximum toughness
C) Moderate strength and toughness
D) Only ductility

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Answer: C) Moderate strength and toughness
Explanation: Bainite is formed at intermediate temperatures, balancing strength and toughness.

Q9. The process of adding carbon to steel at high temperature is called:

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

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Answer: B) Carburization
Explanation: Carburization increases surface carbon content to improve hardness and wear resistance.

Q10. The fracture of brittle materials occurs:

A) Slowly with plastic deformation
B) Suddenly without plastic deformation
C) Only under tension
D) Only under compression

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Answer: B) Suddenly without plastic deformation
Explanation: Brittle fracture occurs almost instantaneously with minimal plastic deformation.