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Chapter 3 Practice Paper: Elements, Compounds and Mixtures — mark scheme

QuizQuipPractice Series
QQ/S1SCI/CH3

Secondary 1 · Lower Secondary Science (G2 / G3)

Mark scheme

Elements, Compounds and Mixtures

Chapter 3 Practice Paper · Maximum mark: 30

Notes for markers

  • Award one mark for each point marked [1], up to the marks shown for the part.
  • Accept answers worded differently that show the same understanding.
  • Units are required where the answer line shows one. ecf: allow an error carried forward.

Section A: Multiple-choice questions[10 marks]

QuestionAnswer
1AAn element is not broken down into simpler substances by chemical methods.1
2CA compound contains two or more elements chemically combined. Its properties differ from those of the elements.1
3BThe parts of sea water are not chemically combined into one substance, so it is a mixture.1
4DThe tablet dissolves, so it is the solute. Water is the solvent. The mixture of the two is the solution.1
5ASmaller pieces give the water more surface to act on, so the crystals disappear sooner. Ice-cold water and no stirring make it slower.1
6CIn a suspension the solid does not dissolve.1
7DThe properties of a compound are different from the properties of the elements in it.1
8BThe constituents keep their own properties and are not chemically joined.1
9AA chemical property describes a chemical change. Melting point, density and colour are physical properties.1
10CRecycling works better when each material is processed with others of the same kind.1

Section B: Structured questions[20 marks]

QuestionAnswer and marking pointsMarks
1(a)

Copper is an element. It cannot be broken down into simpler substances by chemical methods.

  • Element [1]
  • Cannot be broken down into simpler substances by chemical methods [1]
2
1(b)

Air is a mixture. Its gases are not chemically combined.

  • Mixture [1]
  • The gases are not chemically combined / it can be separated by physical methods [1]
2
1(c)

Compound [1]

1
Total for Question 15
2(a)

The solute is the coffee. The solvent is the milk.

  • Coffee is the solute [1]
  • Milk is the solvent [1]
2
2(b)

Any two: use warmer milk; stir; crush the granules.

  • First valid change [1]
  • Second valid change [1]
2
2(c)

The milk cannot dissolve any more coffee. Waiting longer does not increase how much can dissolve.

  • No more coffee can dissolve / the milk is holding as much as it can [1]
1
Total for Question 25
3(a)

The powder is still red-brown, the colour of copper.

  • It is still red-brown / still looks like copper [1]
1
3(b)

The copper and oxygen are not chemically combined. The copper has kept the colour of the element.

  • Not chemically combined [1]
  • Copper has kept a property of the element [1]
2
3(c)

A chemical change has made a new substance. Its properties are different from those of copper.

  • A new substance has formed [1]
  • The properties are different from those of copper [1]
2
Total for Question 35
4(a)

A substance that cannot be broken down into simpler substances by chemical methods. [1]

1
4(b)

Two or more elements chemically combined [1]

1
4(c)

Water contains hydrogen and oxygen chemically combined. It can be broken down into those simpler substances, so it is not an element.

  • Hydrogen and oxygen are chemically combined [1]
  • It can be broken down into simpler substances / its properties differ from those of the elements [1]
2
4(d)

Water [1]

1
Total for Question 45

— End of mark scheme —