Answer:
1. 0.494
2. = 352.299 million years
3. It is between 0 years to 352.299 million years
4. greater than the 352.299 million years.
Explanation:
Given
Uranium 235 ———— lead 207( zircon sample)
t= 0 100%. 0%
t= t. 71%. 29%
1)- half lives elapsed = n
(1/2)n = 0.71
By taking log and solving n = 0.494
No of half lives = 0.494
2) Calculating the age of the larva
- age of lava flow = half life of uranium 235 x n
= 713 x 0.494
= 352.299 million years
3)- The rock layers was created above this lava flow is of later occurrence so the age will be lower than that of the age of the lava flow so the age of rock over the lava flow will lower than the 352.299 million years it will be in between 0 years to 352.299 million years.
4)- The rock layers created underneath this lava flow is of earlier occurrence so its age is more than that of the age of the lava flow so the age of rock will more than the lava flow is greater than the 352.299 million years.
B. The astronomers think the earth was created as all of the other rock materials in our solar system, including the oldest meteorites. The oldest meteorites ever found on Earth contain nearly equal amounts of both Uranium-238 and Lead-206.