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
181–190 of 991
Question 181
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.
Question 182
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 183
2 marks · Normal
Answer and see the solution →State two differences between an atom and a molecule.
Question 184
2 marks · Normal
Answer and see the solution →State what is meant by:
(a)[1 mark]an atom
(b)[1 mark]a molecule
Question 185
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 186
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 187
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 188
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 189
2 marks · Hard
Answer and see the solution →State the meaning of the following terms:
(a)[1 mark]atom
(b)[1 mark]molecule
Question 190
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.