# Material Science Mcqs

Q:

HCP and BCC are called close-packed structures. Close packed structures have:

 A) Highest packing efficiency B) Highest void fraction C) Highest density D) All of the mentioned

Explanation: Due to the largest number of particles in a unit cell, close-packed structures have the highest packing efficiency and hence, lest void fraction. Density is NOT a property of the crystal structure but the substance and depends also on molar mass.

833
Q:

Allotropes differ in which of the following properties:

 A) Atomic Number B) Atomic Mass C) Crystal Structure D) Electronegativity

Explanation: Allotropes are different crystalline structures of the same element. Hence, they have the same atomic number, atomic mass and electronegativity. For e.g., graphite and diamond are allotropes of carbon.

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Q:

X-rays have larger wavelengths than which of the following?

 A) Gamma rays B) Beta rays C) Microwave D) Visible light

Explanation: Larger wavelengths mean less energy. Only gamma rays have higher energy (or shorter wavelengths) than x-rays. Beta rays are actually streaming of particles and have much less energy than x-rays.

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Q:

Greater the angle of inclination of the stress strain curve less is the elasticity.

 A) True B) False

Explanation: IF the angle of inclination of a stress strain curve is high, the elastic zone of the material is more as the curve starts curving after the elastic limit. Hence the elasticity of the material is high.

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Q:

In a hardnability curve which of the following is true:

 A) Hardness increases as distance from quenched end increases B) Hardness decreases as distance from quenched end increases C) Hardness increases as martensite decreases D) Hardenability curve is a straight line

Answer & Explanation Answer: B) Hardness decreases as distance from quenched end increases

Explanation: In a hardenability curve, which is made by keeping hardness number on y-axis and distance from a quenched end at the x-axis. The hardness number decrease as the distance from the quenched end increases.

480
Q:

Which of the following relation is stated by Hooke’s law?

 A) Stress is directly proportional to strain B) Stress is inversely proportional to strain C) Stress is directly proportional to square of strain D) Stress is inversely proportional to square of strain

Explanation: According to Hooke’s law, stress is directly proportional to strain and the ratio of stress to strain is denoted by Y or E and is called Young’s Modulus oof elasticity.

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Q:

In terms of which of the following properties, metals are better than ceramics?

 A) Hardness B) Ductility C) Toughness D) Yield Strength

Explanation: Generally ceramics have equal or better hardness, toughness and yield strength but are highly susceptible to plastic deformation. Even a small stress beyond their yield point leads to fracture.

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Q:

Which type of microscopic technique has been developed that generate topographical maps representing the surface features and characteristics of the specimen?

 A) Optical B) Ultrasonic C) Electron D) Scanning probe