ionically bonded materials
ionically bonded materials
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Revision Questions Booklet
MATERIAL FROM SEMESTER 1 ONLY
This document contains additional questions for practice and revision, both multiple choice questions and
short answer questions. Answers are provided but only at the end to allow you to complete these in
something approximating exam conditions. Written answers are brief, and more detail may be needed in an
exam. Although numerical answers are given where necessary, it is up to you to do the working out. Please
note that in an open book final exam, certain questions that simply require recall of course material without
calculation or analysis will not usually be asked – however, some questions of this type are present below
for completeness.
Multiple choice:
1. What is the configuration of electrons in fluorine (F)?
a. 1s2 2s2 2p6 3s2 3p6
b. 1s2 2s2 2p6
c. 1s2 2s2 2p5
d. 1s2 2s2 2p6 3s2 3p6 4s1
2. The n=3 principal energy level, or shell, contains s, p and d subshells. How many electrons are
present in the n=3 principal energy level?
a. 8
b. 16
c. 10
d. 18
3. Zinc (Zn) has four stable isotopes, listed below with their relative abundance. Calculate the relative
atomic mass for zinc.
30
64Zn - 48.8% 30
66Zn - 28.1%
30
67Zn - 4.2% 30
68Zn - 18.9%
a. 65.6
b. 65.0
c. 65.4
d. 66.0
4. Which of the following sets of features are characteristic of ionically bonded materials?
a. The bonds between individual molecules are weak, and only tend to have an effect at
relatively low temperatures.
b. They are often ductile, form regular crystal structures and conduct electricity when solid.
c. They can be solids, liquids or gases at room temperature and pressure. Individual molecules
have fixed geometries, but these do not often form large scale crystals.
d. They are ceramics, have regular crystal structures with a high melting point and are often
soluble in water.
5. The elastic modulus or ‘stiffness’ of a material can be determined by:
a. The slope of the linear part of the stress-strain curve
b. The stress value that represents the maximum of the linear part of the stress-strain curve
c. The stress value corresponding to the maximum value of the stress-strain curve
d. The integral of the area under the stress-strain curve
6. In a metal forming process, a metal component is subjected to a tensile stress in two dimensions
(1 and 2) and a compressive stress in the other (3), as shown in the diagram. What is the strain
in the direction of the compressive stress? [ = 0.28, E = 2 GPa]
a. -0.265
b. -0.025
c. -0.215
d. -0.015
7. What is elastic strain recovery?
a. It is the small, permanent plastic strain at which yield stress can be measured accurately.
b. After final fracture of a specimen, the resulting pieces of the specimen are no longer loaded
and decrease in length elastically
c. It is the residual, permanent strain in a specimen that has been stressed beyond yield (i.e.
plastic strain has occurred) and then unloaded
d. It is the reduction in strain when a specimen that has been stressed beyond yield (i.e. plastic
strain has occurred) is unloaded
8. The figure below shows impurities (dark circles) added to an elemental metal (white circles).
Which result(s) represent interstitial solid solution(s)?
a. Result IV only
b. Result II only
c. Result I only
d. Results II and IV
= 500 MPa
= -250 MPa
= 500 MPa
9. An iron-carbon alloy that is 1.00% C by weight is slowly cooled from 1600ºC (see phase diagram
below). Which of the following best describes what will happen?
a. It will start to solidify at about 1465ºC and finish solidifying at about 1353ºC
b. It will start to solidify at about 1493ºC and finish solidifying at about 1147ºC
c. It will all solidify at once at about 1147ºC as this is the eutectic point
d. It will start to solidify at about 800ºC and finish solidifying at about 727ºC
10. Consider the Fe-C phase diagram. An alloy that is 1.00% C by weight is slowly cooled from
1000ºC to 700ºC. Which of the following best describes the result?
a. A 2-phase mixture of ferrite (0.76% C) and Fe3C cementite (6.70% C)
b. A 2-phase mixture of ferrite (0.76% C) and Fe3C cementite (2.14% C)
c. A 2-phase mixture of ferrite (0.02% C) and Fe3C cementite (4.30% C)
d. A 2-phase mixture of ferrite (0.02% C) and Fe3C cementite (6.70% C)
11. Consider the Fe-C phase diagram. An alloy that is 1.00% C by weight is slowly cooled from
1000ºC to 700ºC. Which of the following best describes the result?
a. In mass fraction it will be about 96% ferrite and 4% Fe3C cementite
b. In mass fraction it will be about 85% ferrite and 15% Fe3C cementite
c. In mass fraction it will be about 69% ferrite and 31% Fe3C cementite
d. In mass fraction it will be about 15% ferrite and 85% Fe3C cementite
12. Consider the Fe-C phase diagram. An alloy that is 0.25% C by weight is slowly cooled from
1100ºC to 750ºC. Which of the following best describes the result?
a. A 2-phase mixture of ferrite (0.02% C) and austenite (0.63% C)
b. A 2-phase mixture of ferrite (0.02% C) and Fe3C cementite (6.70% C)
c. A 2-phase mixture of ferrite (0.63% C) and austenite (0.02% C)
d. A single phase of austenite
13. Consider the Fe-C phase diagram. An alloy that is 0.25% C by weight is slowly cooled from
1100ºC to 700ºC. What are the relative amounts of each fraction?
a. About 97% ferrite and 3% Fe3C cementite
b. About 3% ferrite and 97% Fe3C cementite
c. About 69% ferrite and 31% Fe3C cementite
d. About 31% ferrite and 69% Fe3C cementite
14. The copper-silver (Cu-Ag) phase diagram is shown below. What are the approximate relative
proportions of the and phases at the eutectic point?
a. 9% and 91%
b. 23% and 77%
c. 92% and 8%
d. 0% and 100%
15. Using the figure in the question above, what is the highest amount of silver that can form a single
phase solid solution in copper at any temperature?
a. 91%
b. 72%
c. 8%
d. Silver does not form a solid solution in copper
16. Using the Lever rule with a lead-tin alloy (see short answer questions for phase diagram) it is
possible to determine the relative proportions of each phase at a particular temperature and
composition. For a lead-tin alloy with 30% tin, what is the change in the proportion of the liquid
phase upon cooling from 250ºC to 200ºC?
a. Decreases by approximately 45%
b. Increases by approximately 45%
c. Decreases by approximately 20%
d. Increases by approximately 20%
200
300
400
500
600
700
800
900
1000
1100
1200
0 10 20 30 40 50 60 70 80 90 100
Composition (wt % Ag)
T
e
m
p
e
ra
tu
re
(
ºC
) + L
+ L
+
L
17. Using the time-temperature-transformation (TTT) curve for Fe/C, predict what will be formed if a
steel at 800ºC is rapidly cooled to 450ºC, held for 10 seconds, then rapidly cooled to room
temperature.
a. 50% bainite, 50% martensite
b. 75% bainite, 25% pearlite
c. 75% pearlite, 25% martensite
d. 100% bainite
18. A eutectoid iron-carbon alloy is cooled rapidly to 450ºC, held for 100 seconds then quenched to
room temperature. Determine the final product using the TTT curve.
a. About 50% bainite, 50% austenite
b. About 50% bainite, 50% martensite
c. 100% bainite
d. 100% martensite
19. Which of the following is true about ceramics whose bonding is predominantly ionic?
a. Negatively and positively charged ions are arranged in straight chains, branched chains or
crosslinked chains that are held together by electrostatic interactions
b. They have close-packed structures with many nearest neighbours, due to their internal
structure of positive ion cores surrounded by a ‘cloud’ of negative ions that move relatively
freely through the lattice.
c. They have structures that are determined by the relative ratios of the radii of the negatively
and positively charged ions. The optimum structure surrounds each + ion with as many –
ions as possible with the – ions not quite touching each other.
d. They have structures lacking order. Ions are packed together in random arrangement.