MATERIAL SCIENCE MCQ SET 3
Q1. The term โalloyโ refers to:
A) Pure metal
B) Mixture of metals
C) Metal oxide
D) Ceramic
Answer: B) Mixture of metals
Explanation: Alloys are metallic mixtures designed for enhanced mechanical properties.
Q2. The metal with the highest thermal conductivity is:
A) Iron
B) Copper
C) Aluminum
D) Lead
Answer: B) Copper
Explanation: Copper is widely used in heat exchangers and electrical conductors due to high conductivity.
Q3. Hardness of a material can be measured by:
A) Rockwell test
B) Brinell test
C) Vickers test
D) All of the above
Answer: D) All of the above
Explanation: Rockwell, Brinell, and Vickers are standard hardness testing methods.
Q4. Precipitation hardening is primarily used for:
A) Ferrous metals
B) Non-ferrous alloys
C) Ceramics
D) Polymers
Answer: B) Non-ferrous alloys
Explanation: Aluminum and copper alloys are hardened by precipitating fine particles to obstruct dislocation motion.
Q5. The ability of a material to resist sudden fracture under impact load is:
A) Toughness
B) Ductility
C) Hardness
D) Brittleness
Answer: A) Toughness
Explanation: Tough materials absorb energy before failure; measured by Charpy or Izod impact tests.
Q6. The process used to relieve internal stresses in cold-worked metals is called:
A) Annealing
B) Normalizing
C) Tempering
D) Hardening
Answer: A) Annealing
Explanation: Annealing softens metal and removes internal stresses caused by cold working.
Q7. The crystal structure of diamond is:
A) BCC
B) FCC
C) HCP
D) Tetrahedral covalent
Answer: D) Tetrahedral covalent
Explanation: Diamond has a 3D tetrahedral structure of covalent bonds, making it extremely hard.
Q8. Which alloy is commonly used for aircraft components?
A) Brass
B) Aluminum-copper alloy
C) Steel
D) Bronze
Answer: B) Aluminum-copper alloy
Explanation: Lightweight and strong Al-Cu alloys are widely used in aerospace applications.
Q9. Pearlite in steel is a mixture of:
A) Ferrite and cementite
B) Austenite and martensite
C) Martensite and bainite
D) Ferrite and martensite
Answer: A) Ferrite and cementite
Explanation: Pearlite is a lamellar mixture of soft ferrite and hard cementite, giving balanced strength and ductility.
Q10. Which of the following metals is most corrosion-resistant?
A) Iron
B) Aluminum
C) Copper
D) Gold
Answer: D) Gold
Explanation: Gold is chemically inert and does not easily oxidize, making it highly corrosion-resistant.
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