AQA GCSE PHYSICS · PAPER 1 · FOUNDATION & HIGHER
Exam Practice: Nuclear equations
Nuclear equations · Atomic structure · Lesson 5 of 10 · 12 marks · 13 minutes
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Instructions
• Answer all the questions.
• Write your answers in the spaces provided.
• The marks for each question are shown in brackets - use this as a guide to how much to write.
• The answers are on separate pages at the back. Attempt every question before you look at them.
• Answer all questions. Use the mark allocation as a guide to how much to write.
Question 1 COMPLETE (2 marks)
Radium-226 decays by emitting an alpha particle: ²²⁶₈₈Ra → ^A_ZRn + ⁴₂He. Write the values of A and Z.
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(Total for Question 1 = 2 marks)
Question 2 COMPLETE (2 marks)
Carbon-14 decays by beta emission: ¹⁴₆C → ¹⁴_ZN + ⁰₋₁e. Write the value of Z.
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(Total for Question 2 = 2 marks)
Question 3 COMPLETE (3 marks)
Complete the nuclear equation for the alpha decay of polonium: ²¹⁴₈₄Po → ^A₈₂Pb + ⁴₂He.
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(Total for Question 3 = 3 marks)
Question 4 EXPLAIN (3 marks)
Explain why the atomic number of a nucleus increases by 1 in beta decay but its mass number does not change.
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(Total for Question 4 = 3 marks)
Question 5 STATE (2 marks)
State what happens to the mass number and the atomic number when a nucleus emits a gamma ray.
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(Total for Question 5 = 2 marks)
TOTAL FOR PAPER = 12 MARKS
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Answers and mark scheme
Check your answer only once you have written one.
Question 1 (2 marks)
A = 222, Z = 86
• A = 222 1 mark
• Z = 86 1 mark
Question 2 (2 marks)
6 = Z − 1, so Z = 7
• Balances atomic numbers 1 mark
• Z = 7 1 mark
Question 3 (3 marks)
214 = A + 4, so A = 210. (Atomic numbers: 84 = 82 + 2.)
• Mass number balance 1 mark
• A = 210 1 mark
• Checks atomic numbers 1 mark
Question 4 (3 marks)
In beta decay a neutron changes into a proton and a fast electron is emitted. The number of protons increases by 1, so the atomic number increases; the total number of protons and neutrons stays the same.
• Neutron turns into a proton 1 mark
• Atomic number increases by 1 because there is one more proton 1 mark
• Number of nucleons unchanged 1 mark
Question 5 (2 marks)
Neither changes.
• Mass number does not change 1 mark
• Atomic number does not change 1 mark