Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Atoms and molecules
20 practice questions
Practice questions
11–20 of 20
Question 11
1 mark · Normal
Answer and check →Which statement best describes a molecule?
- A.A single atom of an element
- B.Two or more atoms chemically bonded together
- C.A mixture of different elements
- D.A group of unbonded atoms
Question 12
2 marks · Normal
Answer and see the solution →State two differences between an atom and a molecule.
Question 13
2 marks · Normal
Answer and see the solution →State what is meant by:
(a)[1 mark]an atom
(b)[1 mark]a molecule
Question 14
4 marks · Normal
Answer and see the solution →This question is about atoms and molecules.
(a)[1 mark]Copper (Cu) is an element. State what you would have if you kept cutting a piece of copper into smaller pieces until you could not cut it any further and still have copper.
(b)[1 mark]Describe what a molecule is.
(c)[1 mark]Give one example of a substance made of molecules that contain atoms of different elements.
(d)[1 mark]Explain why all molecules are made up of atoms, but not all atoms are part of molecules.
Question 15
3 marks · Normal
Answer and see the solution →Methane (CH₄) is a molecule made from one carbon atom and four hydrogen atoms. Calculate the total number of atoms in five molecules of methane. Show your working.
Question 16
3 marks · Normal
Answer and see the solution →Helium exists as separate atoms, while oxygen exists as O₂ molecules. Use your knowledge of atoms and molecules to explain why.
Question 17
4 marks · Normal
Answer and see the solution →Use the table to answer the questions about atoms and molecules.
Substance Formula Atoms present Hydrogen H2 H Carbon dioxide CO2 C and O Argon Ar Ar (a)[1 mark]Which substance in the table consists of single atoms, not molecules? Explain your answer.
(b)[1 mark]State the number of different types of atoms in a carbon dioxide molecule. Give your reasoning.
(c)[1 mark]For hydrogen, state how many atoms are bonded together in each molecule.
(d)[1 mark]Explain what is meant by a molecule, using an example from the table.
Question 18
2 marks · Hard
Answer and see the solution →State the meaning of the following terms:
(a)[1 mark]atom
(b)[1 mark]molecule
Question 19
5 marks · Hard
Answer and see the solution →Ammonia has the chemical formula NH₃.
(a)[1 mark]State what an atom is.
(b)[1 mark]Describe what is meant by a molecule.
(c)[1 mark]How many atoms are present in one molecule of ammonia?
(d)[1 mark]Write the names of the elements that form a molecule of ammonia.
(e)[1 mark]Explain, using ammonia as an example, how a molecule is different from an atom.
Question 20
2 marks · Hard
Answer and see the solution →Give one similarity and one difference between atoms and molecules.
(a)[1 mark]State one way in which atoms and molecules are similar.
(b)[1 mark]State one way in which atoms and molecules are different.