ENGR31 Test 1 Questions

Which one of the following is NOT a close packed crystal structure? (a) BCC, (b) FCC, (c) HCP, (d) all of the above, (e) none of the above.

(a) BCC,

If the temperature were increased we would expect the diffusion flux of atoms to: (a)Increase, (b)Remain unchanged, (c)Decrease, (d)None of the above.(e)

(a)Increase,

The solute is an element or compound present in the greatest amount. (a) True, (b) False.

(b) False.

Which type of brackets is used to enclose a family of equivalent directions? (a) parenthesis, (b) angle brackets, (c) square brackets, (d) curly brackets, (e) quotation marks

(b) angle brackets,

Is it possible to produce a perfect crystalline solid that does not contain any vacancies? (a)Yes, (b)No, (c)Sometimes, (d)Maybe, (e)None of the above.

(b)No,

*Which of the following is NOT a point defect in solids? (a)vacancy, (b)dislocation, (c)self-interstitial, (d)substitutional, (e)all of the above.

(b)dislocation,

The coordination number in the BCC crystal structure is: (a) 4, (b) 6, (c) 8, (d) 12, (e) 16.

(c) 8,

Which of the following has a bond that is the least ionic in character? (a) NaCl, (b) CH4, (c) H2, (d) H2O, (e) Can not be decided.

(c) H2,

Generally speaking, which of the following materials has the least hardness? (a) Metals, (b) Ceramics, (c) Plastics, (d) Metal alloys, (e) all are the same.

(c) Plastics,

The total movement of atoms across an interface will increase when the concentration gradient and the diffusion coefficient: (a)Increases, decreases; (b)Decreases, increases; (c)Increases, increases; (d)Decreases, de-creases; (e)None of the above.

(c)Increases, increases;

Which of the following is a point defect in solids? (a)pores, (b)dislocations, (c)vacancies, (d)grain boundaries, (e)all of the above.

(c)vacancies,

*The coordination number in the FCC crystal structure is: (a) 4, (b) 6, (c) 8, (d) 12, (e) 16.

(d) 12,

*The coordination number in the HCP crystal structure is: (a) 4, (b) 6, (c) 8, (d) 12, (e) 16.

(d) 12,

Which of the following materials may form crystalline solids? (a) Polymers, (b) Metals, (c) Ceramics, (d) All of the above, (e) None of the above.

(d) All of the above,

Copper and Nickel are soluble at all proportions due to: (a)they have similar atomic size, (b)they have the same crystal structure, (c)they have similar electronegativity, (d)all of the above, (e)just a coincidence.

(d)all of the above,

[unchecked]Which of the following exhibits an equivalency of the corner and face positions? (a) BCC, (b) FCC, (c) HCP, (d) all of the above, (e) none of the above.

(e) none of the above.

What is diffusion?

Substance transporting from an area of high concentration to an area of low concentration

The number of whole atoms in the BCC crystal unit structure is: a) 2 b) 4 c) 6 d) 8 e) 10

a) 2

*The total number of atoms (wholly owned and partially owned) in the BCC crystal structure unit cell is: a) 9 b) 10 c) 12 d) 14 e) 17

a) 9

*Generally speaking, which of the following process is the fastest? a) inter-diffusion b) self-diffusion c) vacancy diffusion d) interstitial diffusion e) none

a) inter-diffusion

Because of their characteristic type of bonding, these materials have good ductility and good electrical and thermal conductivity: a) metals b) ceramics c) polymers d) composites e) none

a) metals

The material properties is determined by the material a) structure b) process c) performance d) all e) none

a) structure

*The material properties is determined by the material a) structure b) process c) performance d) all e) none

a) structure *remember PSPP Process>Structure>Properties>Performance

Which of the following is the indices for a plane connected by two parallel edges and two parallel face diagonals in a cubic unit cell? *Which of the following is the direction for a face diagonal in a cubic cell? a) 1 1 1 b) 1 1 0 c) 1 0 0 d) 0 0 0 e) none

b) 1 1 0

In the crystal structure, the direction of atoms touching one another is the direction of close-packing. For FCC unit cell, which of the following direction is a direction of close-packing? a) 100 b) 110 c) 111 d) 112 e) 211

b) 110

The number of whole atoms in the FCC crystal unit structure is: a) 2 b) 4 c) 6 d) 8 e) 10

b) 4

*The lengths of the sides of the unit cell are known as: a) coordination numbers b) lattice parameters c) packing factors d) miller indices e) none

b) lattice parameters

[unchecked]Diffusion will tend to be more rapid for all of the following except a) a material with a lower melting point b) movement of substitutional atoms rather than interstitial c) movement in metals as opposed to ionic-bonded materials. d) movement through BCC structures rather than denser packed FCC e) none

b) movement of substitutional atoms rather than interstitial

*Which of the following is the indices for a face in a cubic unit cell? a) 1 1 1 b) 1 1 0 c) 1 0 0 d) 0 0 0 e) none

c) 1 0 0

*In the crystal structure, the direction of atoms touching one another is the direction of close-packing. For BCC unit cell, which of the following direction is a direction of close-packing? a) 100 b) 110 c) 111 d) 112 e) 211

c) 111

*The number of whole atoms in the HCP crystal unit structure is: a) 2 b) 4 c) 6 d) 8 e) 10

c) 6

*If the properties of a crystal are different in different directions, the crystal is said to be: a) allotropic b) homogeneous c) anisotropic d) asymmetric e) none

c) anisotropic

*Upon cooling from red hot to room temperature, iron changes crystal structure from FCC to BCC. Because the new BCC structure has ______ efficient packing, the same number of atoms now occupies________ space and the piece of iron _______. a) more, less, contracts b) more, more, expands c) less, more, expands d) less, less, contracts e) less, less, expands

c) less, more, expands

*The material class that is limited by its relatively low strength and poor suitability for use at high temperature is: a) metals b) ceramics c) polymers d) composites e) none

c) polymers

*Which of the following properties would generally be considered NOT be considered "high" or "good" for ceramics? a) melting point b) stiffness c) thermal conductivity d) corrosion resistance e) none

c) thermal conductivity

*A plane intercepts the coordinate axes at x=3, y=2, z=1. The Miller Indices of the plane are: a) 1/3 1/2 1 b) 6 3 2 c) 3 2 1 d) 2 3 6 e) 1 2 3

d) 2 3 6

A plane intercepts the coordinate axes at x=1, y=3, z=1/2. The Miller Indices of the plane are: a) 1 1/3 2 b) 6 2 3 c) 3 2 6 d) 3 1 6 e) 6 1 3

d) 3 1 6

A substitutional point defect is a) a lattice point with no atom in it b) an atom at a location that is not a lattice point c) a type of point defect that only occurs in ionic crystals d) a different type of atom occupying a lattice point e) none

d) a different type of atom occupying a lattice point (hence substitution)

*When the atomic bonding is very strong, we would expect the material to possess all but which of the following? a) high strength b) high stiffness c) high melting point d) high coefficient of thermal expansion e) none

d) high coefficient of thermal expansion

*In cubic crystal systems, a plane and a direction that have the same Miller indices are: a) not related b) related, depending on the exact indices c) parallel to each other d) perpendicular to each other e) none

d) perpendicular to each other

*This type of bonding is really an intermolecular attraction, rather than an interatomic one: a) ionic b) covalent c) metallic d) van der Waals e) none

d) van der Waals

*What is the predominant type of bonding for titanium(Ti)? a) ionic b) hydrogen c) covalent d) van der Waals e) metallic

e) metallic

Which of the following are NOT valid Miller Indices? a) 113 b) 013 c) -132 d) 111 e) none

e) none