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The half life of a radioactive isotope ‘X’ is 20 years. It decays to another element ‘Y’ which is stable. The two elements ‘X’ and ‘Y’ were found to be in the ratio of 1 : 7 in a sample of a the given rock. The age of the rock is estimated to be
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- 60 years
- 80 years
- 100 years
- 40 years
Correct Option: A
The value of x is 1/8
| = | = | |||
| 8 | 23 |
⇒ t = 3T = 3 × 20 = 60 years
Hence the estimated age of the rock is 60 years
| X | → | Y0 | |
| N0 | O | ||
| N | N0 - N |
| = | = | = | ||||||
| N0 - N | 7 | N0 | 8 |
t = 3T
= 3 × 20 = 60 years
