Chapter 4 Practice Paper: Chemical Bonding and Structure — question paper (print)

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Secondary 3 · Chemistry (G2 / G3)

Chapter 4 Practice Paper

Chemical Bonding and Structure

Duration: 40 minutes

Total: 30 marks

Name:

Class:

Date:

READ THESE INSTRUCTIONS FIRST

Write your name, class and register number in the spaces at the top of this page.
Answer all questions.
Give numerical answers correct to 3 significant figures unless stated otherwise, with units where a quantity is calculated.
Chemical equations should be balanced, with state symbols shown where the question asks for them.
The number of marks is given in brackets [ ] at the end of each question or part question.
The total number of marks for this paper is shown on its cover.

Original practice material written for the MOE Chemistry syllabus. It is not an official MOE or school examination paper. Chapter 4 (ionic, covalent and metallic bonding; structures and properties).

For Examiner’s Use
Section A	/ 10
Section B	/ 20
Total	/ 30

Section A: Multiple-choice questions[10 marks]

Choose the one correct answer for each question.

1
Which formula matches the ions Mg²⁺ and PO₄³⁻?
1. AMgPO₄
2. BMg₃(PO₄)₂
3. CMg₂(PO₄)₃
4. DMg(PO₄)₃
( )
2
A substance melts at −117 °C and does not conduct in any state. Its structure is
1. Agiant ionic
2. Bgiant molecular
3. Csimple molecular
4. Dmetallic
( )
3
The number of covalent bonds formed by one oxygen atom in a molecule of O₂ is
1. Aone double bond
2. Bone single bond
3. Ctwo single bonds
4. Done triple bond
( )
4
Why does solid potassium iodide not conduct, while molten potassium iodide does?
1. Amelting creates the ions
2. Bmelting destroys the covalent bonds
3. Cthe ions are fixed in the solid lattice but free to move when molten
4. Dthe electrons flow only at high temperature
( )
5
Which statement about the uses of graphite and diamond is correct?
1. Agraphite cuts glass because it is the hardest natural substance
2. Bdiamond is used in pencil leads because its layers slide
3. Cdiamond conducts electricity, so it is used in electrodes
4. Dgraphite is used as a lubricant because its layers slide easily
( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided. Where a question says "in terms of structure and bonding", name the structure and the moving particles.

1
Aluminium (2.8.3) and oxygen (2.6) react to form aluminium oxide.
1. (a)
  State the formula and charge of the ion formed by each element, with a reason.
  [2]
2. (b)
  Deduce the formula of aluminium oxide, showing how the charges balance.
  [2]
3. (c)
  Name the structure type of aluminium oxide and state one property consistent with it.
  [1]
2
Drawings of two molecules are described: molecule P has one atom bonded to three identical atoms by three shared pairs in total; molecule Q has a central atom joined to two outer atoms by two shared pairs each.
1. (a)
  Identify P and Q from Chapter 4’s common molecules.
  [2]
2. (b)
  State how many electrons each central atom shares in total, and why this fills its outer shell.
  [2]
3. (c)
  State one property that both P and Q share at room temperature, and explain it.
  [1]
3
A jeweller’s catalogue describes two forms of carbon.
1. (a)
  Explain why diamond is extremely hard, referring to its structure.
  [2]
2. (b)
  Explain why graphite leaves marks on paper but diamond does not.
  [2]
3. (c)
  Both substances have very high melting points. State the reason common to both.
  [1]
4
Five solids are tested: P conducts as a solid and can be hammered into shape; Q is a gas at room temperature; R conducts only when molten; S never conducts and melts at 1610 °C; T conducts as a solid but is soft and slippery.
1. (a)
  Match each solid to its structure type.
  [4]
2. (b)
  State what would be observed when R is hammered, and explain why.
  [1]

— End of paper —