Chapter 8 Practice Paper: Atoms and Molecules — 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

   Which of these particles is negatively charged?

   1. Aelectron
   2. Bproton
   3. Cneutron
   4. Dnucleus
   ( )
2. 2

   In a model of a helium atom, the two protons and two neutrons account for nearly all the mass. They are found in the

   1. Aelectron cloud only.
   2. Bspace between atoms.
   3. Cnucleus.
   4. Dmolecule of water.
   ( )
3. 3

   Atom P is neutral and has proton number 11. Atom Q is neutral and has proton number 17. Which statement is correct?

   1. ABoth atoms have 12 electrons.
   2. BAtom Q has more electrons than atom P.
   3. CAtom P has 24 electrons.
   4. DNeither atom has any electrons.
   ( )
4. 4

   Gold atoms in a ring and gold atoms in a coin match in one count. That count is the

   1. Anumber of neutrons.
   2. Bmass.
   3. Cnumber of molecules.
   4. Dnumber of protons.
   ( )
5. 5

   A gas jar is labelled sulfur dioxide, SO₂. Each molecule in that jar contains how many atoms?

   1. A3
   2. B2
   3. C1
   4. D4
   ( )
6. 6

   CO₂ contains

   1. A2 carbon atoms and 1 oxygen atom.
   2. B1 carbon atom and 1 oxygen atom.
   3. C1 carbon atom and 2 oxygen atoms.
   4. D2 carbon atoms and 2 oxygen atoms.
   ( )
7. 7

   The formula O₂ represents

   1. Aa mixture.
   2. Ba single atom.
   3. Can ion.
   4. Da molecule of an element.
   ( )
8. 8

   Methane in a cooker flame is carbon and hydrogen atoms chemically joined. Methane is

   1. Aa single atom of carbon.
   2. Ba compound.
   3. Ca mixture of carbon powder and hydrogen gas that are not combined.
   4. Da neutron.
   ( )
9. 9

   A cheek cell and one carbon atom from inside it are compared. The carbon atom is

   1. Avastly smaller.
   2. Babout the same size.
   3. Clarger than a grain of sand.
   4. Dlarge enough to see without a model.
   ( )
10. 10

    A neutron has

    1. Aa negative charge.
    2. Ba positive charge.
    3. Cno charge.
    4. Dthe same charge as an electron.
    ( )

Section B: Structured questions[20 marks]

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

1. 1

   An atom has protons, neutrons and electrons.

   1. (a)

      A diagram of a helium atom labels two protons packed in the centre. State their charge and the name of that central region.

      [1]
   2. (b)

      The diagram shows two other particles outside that region. State their charge and where they are drawn.

      [1]
   3. (c)

      State the charge of a neutron.

      [1]
   4. (d)

      This helium atom has 2 protons and 2 electrons. Explain why a charge detector reads zero for the whole atom.

      [2]
2. 2

   A molecule has the formula NH₃.

   1. (a)

      How many nitrogen atoms does the formula NH₃ show?

      [1]
   2. (b)

      How many hydrogen atoms does the formula NH₃ show?

      [1]
   3. (c)

      Explain whether NH₃ is an element or a compound.

      [2]
   4. (d)

      Using NH₃ as the example, state what must be true before a particle is called a molecule.

      [1]
3. 3

   Two neutral atoms each have 17 protons. Atom X has 18 neutrons. Atom Y has 20 neutrons.

   1. (a)

      State whether X and Y are the same element.

      [1]
   2. (b)

      State the reason.

      [1]
   3. (c)

      Atom X is one of the neutral atoms above. Write down its electron number.

      [1]
   4. (d)

      Explain why the different number of neutrons does not make a different element.

      [2]
4. 4

   Atoms are too small to see, and knowledge of them has been used in more than one way.

   1. (a)

      A sesame seed, a carbon atom and a cheek cell are three objects. List them from the smallest to the largest.

      [1]
   2. (b)

      Explain why a model is used for the atom.

      [2]
   3. (c)

      A government pays for a cancer treatment that uses knowledge of the nucleus, and also for a weapon that uses the same knowledge. Explain why choosing between those uses is not only a science question.

      [2]