Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Principles of Chemistry
991 practice questions
Topics covered
- States of Matter102 practice questions
- Elements, Compounds and Mixtures69 practice questions
- Atomic Structure108 practice questions
- The Periodic Table103 practice questions
- Chemical Formulae, Equations and Calculations Part 119 practice questions
- Chemical Formulae, Equations and Calculations Part 2144 practice questions
- Ionic Bonding143 practice questions
- Covalent Bonding68 practice questions
- Metallic Bonding19 practice questions
- Electrolysis198 practice questions
Practice questions
81–90 of 423 · Normal
Question 81
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 82
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 83
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 84
2 marks · Normal
Answer and see the solution →State the relative charge and relative mass of a neutron.
Question 85
4 marks · Normal
Answer and see the solution →Use the periodic table and your knowledge to answer the following questions about atomic numbers and mass numbers.
(a)[1 mark]Define mass number.
(b)[3 marks]An atom of element X has atomic number 9 and mass number 19.
State how many protons, neutrons and electrons are present in a neutral atom of X.
Question 86
3 marks · Normal
Answer and see the solution →An atom of magnesium has atomic number 12 and mass number 25.
Calculate the number of neutrons in this atom. Show your working.
Question 87
3 marks · Normal
Answer and see the solution →Explain the difference between the atomic number and the mass number of an atom. Give an example of each.
Question 88
4 marks · Normal
Answer and see the solution →The table below shows information about three atoms.
Properties of three atoms Atom Atomic number Mass number A 6 14 B 8 16 C 11 23 (a)[2 marks]For atom A, state the number of protons, neutrons and electrons (assuming atom A is neutral).
(b)[2 marks]Which atom in the table has the greatest number of neutrons? Show your reasoning.
Question 89
1 mark · Normal
Answer and check →Which statement about isotopes is correct?
- A.Isotopes have different numbers of protons but the same number of neutrons.
- B.Isotopes have the same number of protons but different numbers of neutrons.
- C.Isotopes have different atomic numbers but the same mass number.
- D.Isotopes have different numbers of electrons only.
Question 90
2 marks · Normal
Answer and see the solution →Name the three types of sub-atomic particles in an atom and state where each is located.