Question

Chapter 2 Fundamental Concepts 77 c. Your rock contains Iparent isotope A and daughter isotope B. Geochron Laborato- ries dates the rock specimen at 500 million vears old. What is the hall-life of isotope A? d. Your rock contains a parent isotope Sand daughter isotope 7. Geochron Laboratories dates the rock specimen at 200 million vears old.'What is the half-life of isotope S? Geochron has also told you that one of its lab technicians split the rock in half and accidentally crushed part of it and lost it down the sink drain. Does this affect the dating of your rock specimen? Figure 2.26 (page 81) shows the decay curve for a specific isotope X. Refer to the curve and answer the following questions e. If a rock is 100 million vears old, what percentage of isotope X is present? f. If 35% of isotope X is present in a rock, what is the rock's age? 8. If a rock is 400 million years old, what percentage of the daughter isotope, Y. is present? Figure 2020 Tienemy FIGURE 2.26 Decay curve for isotope X b. Write a brief narrative description of the roologie history for the cross section

Answer 1

Chapter 2 Fundamento Concepts 77 explanation: half-life time is the time for which parent isotope quantity become half of its initial quantiy. here parent c. Your rock contains parents to and daughter isotope Gexchron Laborato es dates the rock specimen at 500 million years old. What is the half-le of isotope A? Isopote quanty-1/2, and age of rock - 500 m.y, therefore this age is equal to the half life time 500 m.y d. Your rock contains parentiste Sand dauphier istope T. Goochron Laboratories dates the rock specimen at 200 million years old. What is the half-life of isotope S7 Geochron has also told you that one of its lab technicians split the rock in half and accidentally crushed part of it and lost it down the sink drain. Does this affect the dating of your rock specimen 100 million years age of specimen (t) - 200 million years if n be the number of half life elapse by the specimen , then (1/2)^n = 114. therefore n=2. ethe half-life time, then T = (t/n) - (2002 ) - 100 m. y Figure 2.26 (page 81) shows the decay curve for a specific isotope X. Refer to the n answer the following questions. e. If a rock is 100 million years old, what percentage of isotope X is present? 70 percentage I. If 35% of isotope X is present in a rock, what is the rock's age? 360 m.y 3. If a rock is 400 million years old, what percentage of the daughter isotope, Y, is present? percentage of parent remain=25 therefore the percentage of daughter isotope Y = ( 100 - 25) = 75

Chapter 2: Fundamental Concepts 81 NB remaining parent a 101 FIGURE 2.26 Decay curve for isotope X °360 m.y