Assume that a particular radioactive-isotope dating method has a half-life of 150 million years. Also assume that the parent isotope is commonly incorporated in igneous-rock minerals but that the daughter isotope is not
Measurements show that one crystal in an igneous rock contains 5 million atoms of the parent isotope and 75 million atoms of the daughter isotope. How old is this crystal?
What will be an ideal response?
5 million parent isotope + 75 million of the daughter isotope = 80 million parent isotope as the clock starts
Parent Daughter Half-lives
80 million 0 0
40 million 40 million 1
20 million 60 million 2
10 million 70 million 3
5 million 75 million 4
4 half-lives have gone by. If each half-life takes 150 million years, then the age of the crystal is 600 million years old (150 million years/half-life x 4 half-lives = 600 million years old).
You might also like to view...
Transportation is the source for 77 percent of this pollutant
A) carbon monoxide B) nitrogen oxides C) sulfur dioxide D) volatile organic compounds
In the world map below the color that represents soils that swell and shrink excessively is
A) pink.
B) light green.
C) medium blue.
D) purple.
What is a possible consequence of overpumping of groundwater?
A) Inflation of the aquifer due to an increase in porosity B) Flooding due to rising groundwater levels C) Along the coast, pulling saltwater into wells that were previously fresh D) All of these are correct.
Which event is best represented by the hydrograph shown here?
A) A summer thunderstorm
B) A very long period of steady light rain
C) A long drought with no rain for months
D) A winter snowstorm followed by very cold weather