Question

stratigraphy which of the following statements is true about the to the right: a. fossil 1 is older than fossil 2. b. fossil 3 is younger than fossil 1. c. fossil 2 is the same age as fossil 1. d. fossil 4 is the oldest fossil in this diagram. radioactive decay uranium - 235 is a radioactive atom that is used to determine the absolute age of rocks/fossils. use the half - life graph pictured below to answer the following questions: 1. what is the definition of half - life? 2. what is the half - life of uranium - 235? 3. what percent of uranium - 235 is remaining after 1600 years? 4. if a sample is found to have 10% uranium - 235, how old is it? uranium - 235 decay percent remaining time (millions of years)

Explanation:

Step1: Define half - life

Half - life is the time required for half of the atoms of a radioactive substance to decay.

Step2: Determine U - 235 half - life

From general knowledge, the half - life of Uranium - 235 is 704 million years.

Step3: Find remaining percentage at 1600 years

We need to estimate from the graph. Locate 1600 on the x - axis (time in millions of years), then find the corresponding y - value (percent remaining). By estimation, it is around 75%.

Step4: Find age for 10% remaining

Locate 10 on the y - axis (percent remaining) on the graph, then find the corresponding x - value (time in millions of years). By estimation, it is around 2400 million years.

For the stratigraphy question:
In stratigraphy, lower layers are older. Fossil 4 is in the lowest layer, so it is the oldest.

Answer:

For stratigraphy: d. Fossil 4 is the oldest fossil in this diagram.
For radioactive decay:

1. The time required for half of the atoms of a radioactive substance to decay.
2. 704 million years
3. Approximately 75%
4. Approximately 2400 million years