Since radioactive decay proceeds at a constant rate, like the tick – tock of a clock, it provides. Which pair of parents and daughter isotopes is not useful
Answer
Isotope Pairs Not Useful for Radiometric Dating
Radioactive decay proceeds at a constant and measurable rate, which allows scientists to use specific parent-daughter isotope pairs as reliable “geologic clocks.” These isotopes help determine the absolute age of rocks and fossils. However, not all isotope pairs are suitable for this purpose.
✔️ Common Useful Parent-Daughter Isotope Pairs:
- Uranium-238 → Lead-206: Used for dating rocks over millions of years old.
- Potassium-40 → Argon-40: Suitable for volcanic rocks and ash layers.
- Rubidium-87 → Strontium-87: Helpful in dating ancient igneous and metamorphic rocks.
- Carbon-14 → Nitrogen-14: Used for dating recent organic remains up to ~50,000 years old.
❌ Isotope Pair That Is Not Useful:
The isotope pair Carbon-14 → Nitrogen-14 is not useful for dating ancient rocks or geological formations that are millions or billions of years old. This is because:
- Short half-life: Carbon-14 has a half-life of approximately 5,730 years.
- Decay limit: It becomes undetectable in samples older than ~50,000 years.
- Limited application: Only effective for dating once-living materials (e.g., bone, wood, cloth), not rocks or minerals.
🔍 Conclusion:
While radiometric dating is a powerful tool in geology and archaeology, the effectiveness of each method depends on the properties of the isotopes used. Therefore, Carbon-14 to Nitrogen-14 is not suitable for dating ancient geologic materials like igneous rocks, making it the isotope pair that is not useful in that context.