Question 1 of 3
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Draft attempt
Question 1
1(a)
State two safe working procedures when using a sealed gamma source in a school laboratory.
[2 marks]
Select a question diagram to draw on:
Spec: 3.8.1.2(g)
Reasoning
1(b)
Sodium-22 undergoes beta-plus decay to neon-22. Complete the equation: ²²₁₁Na → ²²₁₀Ne + ____ + νₑ.
[2 marks]
Select a question diagram to draw on:
Spec: 3.8.1.4(b), 3.8.1.4(d)
Reasoning
1(c)
Background radiation gives 180 counts in 300 s. With the source at a fixed distance, the detector gives 450 counts in 45.0 s. Calculate the count rate due to the source alone.
[2 marks]
Select a question diagram to draw on:
Spec: 3.8.1.2(h), 3.8.1.2(i)
Reasoning
1(d)
State two changes to the measurement in part (c) that would reduce the random uncertainty in the corrected count rate.
[2 marks]
Select a question diagram to draw on:
Spec: 3.8.1.2(f), 3.1.2(a), 3.1.2(b)
Reasoning
1(e)
In a separate reading, the corrected count rate is 54.0 s⁻¹ at a separation of 0.300 m between source and detector window. Use the inverse-square law to calculate the corrected count rate at 0.750 m.
[2 marks]
Select a question diagram to draw on:
Spec: 3.8.1.2(e)
Reasoning
1(f)
Outline a method to test the inverse-square relationship for the gamma source. Your answer must include one way to control a systematic effect. The result must be tested without requiring a graph.
[5 marks]
Select a question diagram to draw on:
Spec: 3.8.1.2(f), 3.8.1.2(i), 3.1.2(a), 3.1.2(b)
Reasoning
1(g)
A different sample initially contains 2.00 × 10¹³ unstable nuclei and has half-life 4.00 h. Calculate its initial activity in Bq. Use λ = ln 2 / T½.
[3 marks]
Select a question diagram to draw on:
Spec: 3.8.1.3(d), 3.8.1.3(g)
Reasoning