Campbell Essential Biology with Physiology (6th Edition)
6th Edition
ISBN: 9780134711751
Author: Eric J. Simon, Jean L. Dickey, Jane B. Reece
Publisher: PEARSON
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Chapter 14, Problem 7SQ
Summary Introduction
To determine: The age of a rock found by a paleontologist that contain 12 mg of the radioactive isotope potassium 40. The rock contains 3 mg of potassium 40 and half life of potassium 40 mg is 1.3 billion years.
Introduction: The half life time of a radioactive element can determine the age of a rock. Half life time is the interval time period which is required for the decay of an element to its half value from its initial value. It is denoted as T1/2.
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A paleontologist estimates that when a particular rock formed, it contained 12 mg of the radioactive isotope potassium-40. The rock now contains 3 mg of potassium-40. The half-life of potassium-40 is 1.3 billion years. From this information, you can conclude that the rock is approximately ______________ billion years old.
Which parent isotope is most useful for dating samples that are greater than 100 million years old?
a
potassium-40
b
lead-206
c
argon-40
d
uranium-238
Suppose a scientist finds a rock with an interesting fossil. Curious to know the age of the fossil, she takes the rock to a lab. The
lab determines the amount of rubidium (Rb) and strontium (Sr) in the rock. The scientist is familiar with radiometric dating and
knows that she can now calculate the age of the rock, 1, using an isochron. The Rb-Sr isochron equation is
87.
Rb.
[edr – 1]
86
°Sr.
87
87
Sro
86
Sro
86
Sr.
87.
Rb
3.807 and
89.60. In a published table, she finds that
Using the lab's values, she calculates the isotope ratios as
86
Sr.
87
= 0.7129. She also finds that the decay constant,
86
the ratio of strontium-87 to strontium-86 at the formation of the rock was
Sro
2, for rubidium-87 is 1.42 x 10-11.
Use the equation and provided data to calculate t. Put your answer in scientific notation and round to the nearest tenth.
years
x10
What is the approximate age of the rock in billions of years? Round to the nearest tenth.
billions of years
t =
Chapter 14 Solutions
Campbell Essential Biology with Physiology (6th Edition)
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- The most useful method for dating ancient calcium rich cave deposits would be Group of answer choices A: Argon-Argon Dating B: Paleomagnetic Reversals C: Electron Spin Resonance Dating D: Uranium-Thorium Dating E: Potassium-Argon Datingarrow_forwardWhich method is used to assign numerical ages to events or materials? absolute dating half-life dating isotope dating relative datingarrow_forwardRadiometric dating _______. has a substantial error factor can only be used for dating animal fossils can be used to date sedimentary rock, but not fossils is basedon the premise that each isotope decays at a constant rate is unpredictable because of changes in temperature and pressurearrow_forward
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- In radiometric dating, scientists use the half-life of a radioactive isotope, to determine the approximate age of rocks, and the fossils that are embedded in them. Half-life is the time it takes for half of a radioactive element to become stable.Uranium 238 (238U) is a radioactive element that decays into Lead (206Pb) after 4.5 billion years. 6) Scientists found a fossil in a layer of rock that tested as 1/8th U and 7/8th Pb. What is the approximate age of the fossil? A) 562 million years old B) 4.5 billion years old C) 9 billion years old D) 13.5 billion years old Not Gradedarrow_forwardOne problem in radiocarbon dating of biological samples, especially very old ones, is that they can easily be contaminated with modern biological material during the measurement process. What effect would such contamination have on the estimated age? Why is such contamination a more serious problem for samples of older material than for samples of younger material?arrow_forwardA scientist has a fossil that was found in a layer of rock close to Earth’s surface. He believes that the fossil is around 12,000 years old. Which method would best allow the scientist to confirm the actual age of the fossil? finding another fossil in a deeper layer of rock finding another fossil in the same layer of rock using carbon/nitrogen absolute dating using potassium/argon absolute datingarrow_forward
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