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
701–710 of 991
Question 701
1 mark · Normal
Answer and check →Which of the following dot-and-cross diagrams correctly represents the covalent bonding in a molecule of hydrogen chloride, HCl?
- A.A. H and Cl with one shared pair and Cl with 6 additional outer electrons.
- B.B. H and Cl with one shared pair and Cl with only 2 outer electrons.
- C.C. H and Cl with two shared pairs between them.
- D.D. H atom with two electrons, Cl atom with seven electrons, but none shared.
Question 702
2 marks · Normal
Answer and see the solution →Describe what happens to the electrons in the outer shells of two hydrogen atoms when they form a molecule of hydrogen, H.
Question 703
4 marks · Normal
Answer and see the solution →(a)[2 marks]Draw a dot-and-cross diagram to show the covalent bonding in an oxygen (O) molecule.
(b)[2 marks]Explain why there are two covalent bonds between the two oxygen atoms.
Question 704
3 marks · Normal
Answer and see the solution →A molecule of ammonia () is formed by nitrogen bonding covalently with three hydrogen atoms.
Given that each covalent bond is formed by the sharing of one pair of electrons, calculate the total number of electrons that nitrogen shares with hydrogen in ammonia.
Question 705
2 marks · Hard
Answer and see the solution →State what holds the atoms together in a covalent bond, and explain why a covalent bond only forms between certain atoms.
Question 706
5 marks · Hard
Answer and see the solution →Boron trifluoride (BF) is a covalent compound. Answer the following questions about its bonding.
(a)[1 mark]How many electrons are in the outer shell of a boron atom and of a fluorine atom?
(b)[2 marks]Draw a dot-and-cross diagram to show the covalent bonding in a molecule of BF. Use dots (•) for boron’s electrons and crosses (×) for fluorine’s electrons.
(c)[2 marks]Explain, using your diagram, why the central boron atom in BF does not have a full octet in its outer shell.
Question 707
2 marks · Hard
Answer and see the solution →Explain what a covalent bond is and describe how the sharing of electrons holds the bonded atoms together.
Question 708
1 mark · Easy
Answer and see the solution →State whether water (H₂O) has a simple molecular or giant covalent structure.
Question 709
3 marks · Easy
Answer and see the solution →The table shows properties of two substances, X and Y.
Properties of X and Y Substance Relative molecular mass (Mr) Physical state at room temp. Electrical conductivity X 32 gas does not conduct Y 160 liquid does not conduct (a)[2 marks]Which substance, X or Y, has the higher boiling point? Explain your answer.
(b)[1 mark]Suggest why neither substance conducts electricity.
Question 710
2 marks · Easy
Answer and see the solution →Iodine melts at 114°C and boils at 184°C. Calculate the temperature range (in °C) over which iodine is a liquid.