Q: A metal crystallizes in a body-centered cubic (BCC) unit cell with an atomic radius of 138 pm. What is the volume of the unit cell in $\mathrm{pm^3}$?

$5.22 \times 10^8\ \mathrm{pm^3}$

Question 1

Which of the following statements best describes the relationship between coordination number and packing efficiency in a crystal lattice?

Accepted Answer

A higher coordination number results in a higher packing efficiency.

Question 2

A metal crystallizes in a body-centered cubic (BCC) unit cell with an atomic radius of 138 pm. What is the volume of the unit cell in $\mathrm{pm^3}$?

Accepted Answer

$5.22 	imes 10^8\ \mathrm{pm^3}$

Question 3

Which equation correctly relates the edge length $l$ of a body-centered cubic unit cell to the atomic radius $r$?

Accepted Answer

$l = \dfrac{4r}{\sqrt{3}}$

Question 4

Which type of crystalline solid is most likely to have a high melting point and conduct electricity in the solid state?

Accepted Answer

Metallic solid

Question 5

Diamond and graphite are both forms of carbon. Which statement best explains why diamond is much harder than graphite?

Accepted Answer

Diamond consists of carbon atoms bonded in a three-dimensional tetrahedral network by strong covalent bonds.

Question 6

Which of the following best describes the bonding in metallic solids?

Accepted Answer

Atoms are held together by a 'sea' of delocalized electrons.

Question 7

A face-centered cubic (FCC) unit cell contains how many atoms per unit cell?

Accepted Answer

4

Question 8

Which of the following solids is held together primarily by dispersion forces?

Accepted Answer

Solid xenon

Question 9

Which property is NOT characteristic of network covalent solids like diamond?

Accepted Answer

Electrical conductivity

Question 10

Which of the following best explains why graphite is a good lubricant?

Accepted Answer

Graphite is soft because its layers are held together by weak dispersion forces, allowing them to slide past each other.

Question 11

Which of the following is a correct statement about polymers?

Accepted Answer

Polymers can be natural or synthetic and are made by linking together monomers.

Question 12

Which of the following equations is used to calculate the density $d$ of a crystalline solid from its unit cell?

Accepted Answer

$d = \dfrac{m}{V}$

Question 13

Which of the following is a property of ionic solids?

Accepted Answer

High melting point due to strong coulombic forces

Question 14

Which of the following best describes the process of addition polymerization?

Accepted Answer

Monomers link together without the elimination of any atoms.

Question 15

Which of the following is a real-world application of a network covalent solid?

Accepted Answer

Diamond used as an abrasive

Question 16

A crystalline solid is found to have a coordination number of 12. Which type of unit cell is most likely present?

Accepted Answer

Face-centered cubic

Question 17

Which of the following best explains why ionic solids have higher melting points than molecular solids?

Accepted Answer

Ionic solids are held together by strong coulombic forces, while molecular solids are held together by weaker intermolecular forces.

Question 18

Which of the following is a copolymer?

Accepted Answer

A polymer made from two different kinds of monomers

Question 19

Which of the following is true about the structure of graphite?

Accepted Answer

Each carbon atom forms three sigma bonds and one pi bond in a trigonal-planar geometry.

Question 20

Which of the following best describes the difference between a monomer and a polymer?

Accepted Answer

A monomer is a small molecule that can be linked to form a polymer.

Solids and Modern Materials: Structure, Types, and Properties

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