| 1 | A | B | C | D |
| --- | --- | --- | --- | --- |
| 2 | Radiogenic nuclide - Radiogenic nuclides used in geology |  |  |  |
| 3 | Parent nuclide | Daughter nuclide | Decay constant (yr−1) | Half-life |
| 4 | 190Pt | 186Os | 1.477 ×10−12 | 469.3 Gyr * |
| 5 | 147Sm | 143Nd | 6.54 ×10−12 | 106 Gyr |
| 6 | 87Rb | 87Sr | 1.402 ×10−11 | 49.44 Gyr |
| 7 | 187Re | 187Os | 1.666 ×10−11 | 41.6 Gyr |
| 8 | 176Lu | 176Hf | 1.867 ×10−11 | 37.1 Gyr |
| 9 | 232Th | 208Pb** | 4.9475 ×10−11 | 14.01 Gyr |
| 10 | 40K | 40Ar | 5.81 ×10−11 | 11.93 Gyr |
| 11 | 238U | 206Pb** | 1.55125 ×10−10 | 4.468 Gyr |
| 12 | 40K | 40Ca | 4.962 ×10−10 | 1.397 Gyr |
| 13 | 235U | 207Pb** | 9.8485 ×10−10 | 0.7038 Gyr |
| 14 | 129I | 129Xe | 4.3 ×10−8 | 16 Myr |
| 15 | 10Be | 10B | 4.6 ×10−7 | 1.5 Myr |
| 16 | 26Al | 26Mg | 9.9 ×10−7 | 0.7 Myr |
| 17 | 36Cl | 36Ar/S | 2.24 ×10−6 | 310 kyr |
| 18 | 234U | 230Th | 2.826 ×10−6 | 245.25 kyr |
| 19 | 230Th | 226Ra | 9.1577 ×10−6 | 75.69 kyr |
| 20 | 231Pa | 227Ac | 2.116 ×10−5 | 32.76 kyr |
| 21 | 14C | 14N | 1.2097 ×10−4 | 5730 yr |
| 22 | 226Ra | 222Rn | 4.33 ×10−4 | 1600 yr |

Question: How are 206Pb, 207PB and 208PB formed?
Answer: The ²⁰⁶Pb is formed from ²³⁸U, ²⁰⁷Pb from ²³⁵U and ²⁰⁸Pb from ²³²Th.