10-minute Quiz : Chapter 58 Metals and alloys

Which of the following is/are the reason(s) for using aluminium in making cooking utensils?

(1) It is ductile.

(2) It has high thermal conductivity.　

(3) It has a high melting point.

• A. (1) only
• B. (2) only
• C. (1) and (3) only
• D. (2) and (3) only

What is the coordination number for each metal atom in close-packed structures?

• A. 4
• B. 6
• C. 8
• D. 12

In which of the following types of structure do the atoms have the lowest packing efficiency?

• A. Face-centred cubic structure
• B. Hexagonal close-packed structure
• C. Body-centred cubic structure
• D. Cubic close-packed structure

The diagram shows the arrangement of three layers of metal atoms, stacking one above another, in a metallic crystal structure. Which of the following types of structure does the metal have?

• A. Face-centred cubic structure
• B. Hexagonal close-packed structure
• C. Body-centred cubic structure
• D. Cubic close-packed structure

A part of the metallic crystal structure of sodium is shown in the diagram. How many atoms are there in a unit cell of sodium?

• A. 2
• B. 3
• C. 4
• D. 8

Which of the following statements concerning alloys is INCORRECT?

• A. They are harder than pure metals.
• B. They are more corrosion resistant than pure metals.
• C. They have higher melting points than pure metals.
• D. They are less malleable than pure metals.

Direction: Questions 7 and 8 refer to the cubic close-packed structure of a metal.

How many atoms are there in a unit cell of metal with a cubic close-packed structure?

• A. 2
• B. 4
• C. 6
• D. 8

Direction: Questions 7 and 8 refer to the cubic close-packed structure of a metal.

Given that the edge length of the unit cell of this structure is 200 pm. If 200 g of this metal contains 24 × 10²³ atoms, what is the density of this metal?

(Hint: 1 pm = 1 × 10⁻¹⁰ cm)

• A. 63.4 g cm⁻³
• B. 50.3 g cm⁻³
• C. 41.7 g cm⁻³
• D. 34.8 g cm⁻³

Given that the density of lithium is 0.53 g cm⁻³, how many atoms are there in the unit cell of lithium with an edge length of 3.5 × 10⁻⁸ cm?

(Relative atomic mass: Li = 6.9; Avogadro constant = 6.02 × 10²³ mol⁻¹)　

• A. 1
• B. 2
• C. 3
• D. 4

When the carbon content of steel is increased, which of the following properties would be reduced?

• A. Ductility
• B. Brittleness
• C. Strength
• D. Hardness