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
691–700 of 991
Question 691
2 marks · Easy
Answer and see the solution →A phosphorus atom has 5 electrons in its outer shell. How many covalent bonds can it form in a molecule of phosphorus trichloride (PCl3)?
Question 692
2 marks · Easy
Answer and see the solution →Explain, using dot-and-cross diagrams, why a molecule of hydrogen fluoride (HF) contains only one covalent bond.
Question 693
3 marks · Easy
Answer and see the solution →Table 1 shows the number of outer shell electrons and covalent bonds formed by some elements.
Table 1. Covalent bonds and outer electrons Element Number of outer electrons Number of covalent bonds Hydrogen 1 ? Oxygen 6 ? Carbon 4 ? Nitrogen 5 ? Question 694
1 mark · Easy
Answer and see the solution →Draw a dot-and-cross diagram to show a single covalent bond between two bromine atoms in a Br2 molecule.
Question 695
3 marks · Easy
Answer and see the solution →A student claims: ‘All atoms in a covalent bond must supply one electron to the shared pair.’
(a)[2 marks]Is this statement always correct? Give a reason for your answer.
(b)[1 mark]State what a shared pair of electrons is called.
Question 696
2 marks · Easy
Answer and see the solution →Carbon dioxide (CO2) contains two double covalent bonds. How many shared electrons are present in the molecule in total?
Question 697
2 marks · Normal
Answer and see the solution →State what is meant by a covalent bond. Explain the mechanism by which a covalent bond forms between two atoms.
Question 698
4 marks · Normal
Answer and see the solution →(a)[2 marks]Draw a dot-and-cross diagram to show the covalent bonding in a molecule of ammonia (NH).
(b)[2 marks]State the number of bonding pairs and lone pairs of electrons on the nitrogen atom in ammonia.
Question 699
3 marks · Normal
Answer and see the solution →Ethene (CH) is an organic molecule. Explain, using electron arrangement, how you can use a dot-and-cross diagram to confirm that each atom in ethene has a full outer shell.
Question 700
4 marks · Normal
Answer and see the solution →Table 1. Molecules and their covalent bonds Molecule Number of Covalent Bonds per Molecule H2 1 CH4 4 NH3 3 CO2 4 Using the data in Table 1, answer the following questions:
(a)[1 mark]Which molecule contains the greatest number of covalent bonds per molecule?
(b)[2 marks]Explain why CO has four covalent bonds per molecule.
(c)[1 mark]State how many covalent bonds exist in two molecules of ammonia (NH).