Chapter 21 2 Which of these materials has the lowest electrical conductivity

A) materials (1) and (2)

B) materials (1) and (4)

C) materials (2) and (3)

D) materials (3) and (4)

75) Which of these materials has the highest electrical conductivity?

A) material (1)

B) material (2)

C) material (3)

D) material (4)

76) Which of these materials has the lowest electrical conductivity?

A) material (1)

B) material (2)

C) material (3)

D) material (4)

77) Which of these materials has an electrical conductivity that increases with an increase in temperature?

A) materials (1) and (2)

B) materials (1) and (4)

C) materials (2) and (3)

D) materials (3) and (4)

78) Which of these materials has an electrical conductivity that decreases with an increase in

temperature?

A) material (1)

B) material (2)

C) material (3)

D) material (4)

79) Which of these materials has an electrical conductivity that remains constant with an increase in

temperature?

A) material (1)

B) material (2)

C) material (3)

D) material (4)

23

The following pictures show the electron populations of the composite s-d bands for four different

transition metals.

80) Which metal has the highest melting point?

A) metal (1)

B) metal (2)

C) metal (3)

D) metal (4)

81) Which metal has the lowest melting point?

A) metal (1)

B) metal (2)

C) metal (3)

D) metal (4)

82) Which is the hardest metal?

A) metal (1)

B) metal (2)

C) metal (3)

D) metal (4)

The following pictures show the electron populations of the composite s-d bands for Sc, Ti, V, and Zn.

83) Which picture corresponds to Sc?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

84) Which picture corresponds to Ti?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

85) Which picture corresponds to V?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

86) Which picture corresponds to Zn?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

The following pictures show the electron populations of the composite s – d bands for Y, Mo, Ag, and Cd.

87) Which picture corresponds to Y?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

88) Which picture corresponds to Mo?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

89) Which picture corresponds to Ag?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

90) Which picture corresponds to Cd?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

91) In this picture the band gap is given by letter(s)

A) a.

B) b.

C) c.

D) a and b.

92) In this picture the conduction band is given by letter(s)

A) a.

B) b.

C) c.

D) a and b.

93) In this picture the valence band is given by letter(s)

A) a.

B) b.

C) c.

D) a and b.

94) Which picture represents a p-type Si semiconductor?

A) picture (A)

B) picture (B)

C) both picture (A) and picture (B)

D) neither picture (A) nor picture (B)

95) Which picture represents an n-type Si semiconductor?

A) picture (A)

B) picture (B)

C) both picture (A) and picture (B)

D) neither picture (A) nor picture (B)

Picture (1) shows the electron populations of the bands of MO energy levels for elementary silicon.

96) Which picture (1)-(4) shows the electron populations when the silicon is doped with gallium?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

97) Which picture (1)-(4) shows the electron populations when the silicon is doped with arsenic?

A) picture (1)

B) picture (2)

C) picture (3)

D) picture (4)

98) Which schematic best represents the electrical resistance versus temperature curve for a

superconductor?

A) A

B) B

C) C

D) none of these

21.2 Algorithmic Questions

1) What are the most abundant mineral in the earth’s crust?

A) silicates

B) iodides

C) sulfates

D) oxides

2) What minerals are important commercial sources of metals?

A) silicates

B) chlorides

C) nitrates

D) oxides

3) What is a principal commercial ore for the element aluminum?

A) bauxite

B) chalcopyrite

C) galena

D) rutile

4) What is a principal commercial ore for the element iron?

A) bauxite

B) pyrolusite

C) ilmenite

D) hematite

5) What is the most important copper containing ore?

A) bauxite

B) chalcopyrite

C) pyrolusite

D) ilmenite

6) What metal is isolated from the ore galena?

A) lead

B) iron

C) zinc

D) silver

7) What metal is isolated from the ore sphalerite?

A) chromium

B) iron

C) silver

D) zinc

8) What metal is isolated from the ore rutile and what is the chemical formula of rutile?

A) aluminum, Al2O3 ∙ xH2O

B) cassiterite, SnO2

C) cinnabar, HgS

D) titanium, TiO2

9) Which of the following metals occurs in nature principally as oxide ores?

A) Li

B) Cu

C) Cr

D) Ru

10) Which substance is commonly found in nature in an uncombined form?

A) Fe

B) Zn

C) Au

D) Li