Chapter 3 Practice Paper: Elements, Compounds and Mixtures — question paper

Section A: Multiple-choice questions[10 marks]

Answer all questions. For each question, write the letter (A, B, C or D) of the correct answer in the brackets provided.

1. 1

   A substance that cannot be broken down into simpler substances by chemical methods is

   1. Aan element.
   2. Ba compound.
   3. Ca mixture.
   4. Da suspension.
   ( )
2. 2

   Hydrogen and oxygen chemically combined as water form

   1. Aa mixture of two gases.
   2. Ba suspension.
   3. Ca compound.
   4. Dan element.
   ( )
3. 3

   Sea water contains water, dissolved salts and sometimes sand. It is best described as

   1. Aa single element.
   2. Ba mixture.
   3. Cone atom.
   4. Da pure compound with no other substance.
   ( )
4. 4

   A glucose tablet disappears when it is stirred into a glass of water. In that mixture the tablet is the

   1. Asolvent.
   2. Bsolution.
   3. Csuspension.
   4. Dsolute.
   ( )
5. 5

   A cook wants jelly crystals to disappear quickly in a jug of water. Which action helps?

   1. Abreaking the crystals up before adding them
   2. Bstanding the jug in a bowl of ice
   3. Cusing a taller jug that holds the same volume of water
   4. Dleaving the jug still on the table
   ( )
6. 6

   A solid that does not dissolve, and that settles when the mixture is left to stand, is in

   1. Aa solution.
   2. Ban element.
   3. Ca suspension.
   4. Da compound only.
   ( )
7. 7

   Sodium chloride does not behave like the metal sodium. This is because sodium chloride is

   1. Astill the element sodium.
   2. Ba mixture of sodium and chlorine gas.
   3. Ca suspension.
   4. Da compound, with different properties from its elements.
   ( )
8. 8

   A mixture can often be separated by physical methods because the constituents are

   1. Aalways gases.
   2. Bnot chemically combined.
   3. Ca new single element.
   4. Ddestroyed by filtering.
   ( )
9. 9

   Which observation is a chemical property?

   1. AThe substance reacts with acid and a gas is given off.
   2. BThe melting point is 80 °C.
   3. CThe density is 2 g/cm³.
   4. DThe substance is colourless.
   ( )
10. 10

    Sorting plastic bottles away from glass before recycling is useful because

    1. Aevery material has the same melting point.
    2. Bglass is an element.
    3. Cmaterials of the same kind can be processed together.
    4. Dmixtures cannot be separated.
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided. Show your working for calculations.

1. 1

   A student is given three samples: a copper wire, air, and carbon dioxide gas.

   1. (a)

      State whether copper is an element, a compound or a mixture, and give one reason.

      [2]
   2. (b)

      State whether air is an element, a compound or a mixture, and give one reason.

      [2]
   3. (c)

      State whether carbon dioxide is an element or a compound.

      [1]
2. 2

   Instant coffee granules are stirred into cold milk until the granules disappear.

   1. (a)

      In this coffee drink, name the substance that dissolved and the substance that did the dissolving.

      [2]
   2. (b)

      State two changes that would make the next cup of granules disappear sooner.

      [2]
   3. (c)

      Extra granules still sit on the bottom after a long wait. State what this shows about the milk.

      [1]
3. 3

   Red-brown copper powder is sealed in a jar of oxygen. The jar is not heated yet.

   1. (a)

      State one observation that shows the copper is still present as the element.

      [1]
   2. (b)

      Explain why the sealed jar does not yet contain the compound copper oxide.

      [2]
   3. (c)

      The jar is then heated strongly. A black solid forms and the red-brown powder disappears. State what this shows.

      [2]
4. 4

   Use oxygen and water as examples.

   1. (a)

      State what an element is.

      [1]
   2. (b)

      State what a compound is.

      [1]
   3. (c)

      Explain why water is a compound and not an element.

      [2]
   4. (d)

      Name the solvent when salt dissolves in water.

      [1]