Types of Engineering Materials in Chemistry for Engineers

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Which of the following best describes a metal?

A material composed of two or more nonmetals
A rigid, brittle material that is easily fractured
A soft, dull material with poor electrical and thermal conductivity
A solid, shiny material that is typically hard, malleable, and ductile with good electrical and thermal conductivity (correct)

Which type of cast iron has the highest strength and wear resistance?

Gray cast iron
White cast iron (correct)
Malleable cast iron
S.G. (Spheroidal Graphite) cast iron

What is the primary difference between a thermoplastic polymer and a thermosetting polymer?

Thermoplastics are more brittle than thermosets
Thermoplastics can be reshaped by heating, while thermosets cannot be reshaped once formed (correct)
Thermoplastics have higher thermal conductivity than thermosets
Thermoplastics are composed of a single monomer, while thermosets are composed of multiple monomers

What is the main component that differentiates an alloy from a pure metal?

Two or more metals (C) Signup and view all the answers

What is the meaning of the term $\text{polymer}$?

Many units (D) Signup and view all the answers

Which of the following is true about the atomic packing factor (APF) for different crystal structures?

The APF for FCC and HCP structures is the same, which is 0.74. (A) Signup and view all the answers

Which of the following statements about metallic solids is incorrect?

They are typically hard, but not malleable or ductile. (C) Signup and view all the answers

What is the term used to describe materials that have two or more distinct crystal structures?

Polymorphism (B) Signup and view all the answers

Which of the following statements about covalent solids is correct?

They are made up of atoms that are bonded by covalent bonds, forming a giant network solid. (A) Signup and view all the answers

In the context of crystal structures, what is the meaning of the term 'unit cell'?

It is the smallest portion of a crystal lattice that, when repeated in three dimensions, generates the entire crystal structure. (A) Signup and view all the answers

Which of the following statements about molecular solids is incorrect?

The molecules in molecular solids are held by strong covalent bonds. (D) Signup and view all the answers

Which of the following crystal structures has the lowest atomic packing factor (APF)?

Simple cubic (SC) (D) Signup and view all the answers

Which of the following statements about ionic solids is correct?

They are made up of positively and negatively charged ions arranged in a regular fashion, held by strong electrostatic forces of attraction. (D) Signup and view all the answers

Which of the following statements about polycrystalline materials is correct?

They are made up of multiple grains, each of which is a single crystal, and if the grains are randomly oriented, the overall properties are isotropic. (B) Signup and view all the answers