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
221–230 of 991
Question 221
3 marks · Normal
Answer and see the solution →Bromine consists of two isotopes: and . The percentage abundances are 51% and 49% respectively. Calculate the relative atomic mass of bromine. Give your answer to 1 decimal place.
Question 222
3 marks · Normal
Answer and see the solution →Chlorine exists mainly as two isotopes, and . The Periodic Table gives chlorine a relative atomic mass of 35.5.
Explain why this value is not a whole number. Your answer should refer to isotopes and how the value is calculated.
Question 223
4 marks · Normal
Answer and see the solution →The table shows the abundances of three isotopes of element X.
Isotope Relative Mass % Abundance X-10 10 20 X-11 11 50 X-12 12 30 Question 224
1 mark · Normal
Answer and check →Which statement correctly describes all isotopes of an element?
- A.They have the same mass number but different atomic numbers.
- B.They have the same number of protons but different numbers of neutrons.
- C.They have different chemical properties.
- D.They contain the same number of neutrons.
Question 225
2 marks · Normal
Answer and see the solution →An atom of sodium-23 () has how many neutrons?
Question 226
4 marks · Normal
Answer and see the solution →Consider two isotopes of carbon: and .
(a)[1 mark]State the number of protons and neutrons in .
(b)[1 mark]State the number of protons and neutrons in .
(c)[1 mark]Explain why and are considered isotopes of the same element.
(d)[1 mark]Describe one way in which the two isotopes differ.
Question 227
2 marks · Hard
Answer and see the solution →A sample of element Q contains 10% of isotope Q-40 and 90% of isotope Q-42.
Calculate the relative atomic mass of Q. Give your answer to one decimal place.
Question 228
5 marks · Hard
Answer and see the solution →(a)[1 mark]Describe what isotopes are.
(b)[3 marks]The element magnesium has isotopes with mass numbers 24, 25, and 26. Give the number of protons and neutrons in each of these isotopes.
Isotope Number of protons Number of neutrons ^24Mg ^25Mg ^26Mg (c)[1 mark]Explain why magnesium-24, magnesium-25, and magnesium-26 all have the same chemical properties.
Question 229
2 marks · Hard
Answer and see the solution →The element X has two stable isotopes: X-64 (mass = 64, abundance = 73%) and X-66 (mass = 66, abundance = 27%).
Calculate the relative atomic mass of X. Give your answer to one decimal place.
Question 230
1 mark · Easy
Answer and check →State the number of electrons in a neutral atom of lithium, which has an atomic number of 3.