Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Atoms and molecules
20 practice questions
Practice questions
1–10 of 20
Question 1
1 mark · Easy
Answer and see the solution →State the meaning of the term "atom".
Question 2
3 marks · Easy
Answer and see the solution →Answer the following about atoms and molecules.
(a)[1 mark]Define a molecule.
(b)[1 mark]Give an example of a molecule formed from atoms of two different elements.
(c)[1 mark]Explain why atoms of helium (He) are not classed as molecules.
Question 3
2 marks · Easy
Answer and see the solution →A molecule of methane (CH₄) contains one carbon atom and four hydrogen atoms. Calculate the total number of atoms present in three molecules of methane. Show your working.
Question 4
2 marks · Easy
Answer and see the solution →Explain the difference between an atom of oxygen (O) and a molecule of oxygen (O₂).
Question 5
3 marks · Easy
Answer and see the solution →The table shows three simple substances. Use the information to answer the questions.
Atoms in substances Substance Atoms present Hydrogen H₂ Nitrogen N₂ Water H₂O (a)[1 mark]Which of these substances are molecules made from only one type of atom?
(b)[1 mark]How many atoms are present in one molecule of water?
(c)[1 mark]State why water is classified as a molecule.
Question 6
1 mark · Easy
Answer and see the solution →Complete the sentence: A molecule must contain
atom(s).
Question 7
3 marks · Easy
Answer and see the solution →This question is about atoms and molecules.
(a)[1 mark]State what an atom is.
(b)[1 mark]State what a molecule is.
(c)[1 mark]Describe one feature that atoms and molecules have in common.
Question 8
2 marks · Easy
Answer and see the solution →Each molecule of carbon dioxide (CO₂) contains one carbon atom and two oxygen atoms. How many atoms are present in four molecules of carbon dioxide? Show your working.
Question 9
3 marks · Normal
Answer and see the solution →A molecule of ammonia (NH₃) contains both nitrogen and hydrogen atoms.
(a)[3 marks]Calculate the total number of atoms in two molecules of ammonia (NH₃). Show your working.
Question 10
3 marks · Normal
Answer and see the solution →Explain why oxygen can exist as O₂ molecules, but helium does not form molecules under normal conditions. Use your knowledge of atoms and molecules.