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Module 4: Interpreting the past - Geochronology

Quick questions on Radiometric dating and half-life: radioactive decay, parent-daughter ratios and isotopic systems - OCR A-Level Geology

4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.

What is calculating an age from the parent-to-daughter ratio?
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When a mineral crystallises it traps parent atoms but (ideally) no daughter. Over time, parent decays to daughter, so the parent-to-daughter ratio records the age. The method:
What is q1?
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Define the half-life of a radioactive isotope. [1 mark]
What is q2?
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A mineral has a parent-to-daughter ratio of 1:11{:}1. State how many half-lives have elapsed. [1 mark]
What is q3?
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Explain why uranium-lead, not carbon-14, is used to date a 33 billion year old rock. [2 marks]

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