Question 1

A neutron is a combination of a(n)________ and a(n)________.

Accepted Answer

A neutron is made up of one up quark and two down quarks, which can be simplified to the concept of being a combination of an electron (- charge) and a proton (+ charge) in terms of charge balance, not literal composition.

Question 2

What is the definition of a half-life?

Accepted Answer

A half-life is the time it takes for half of the parent isotope to decay to the daughter.

Question 3

For what reason might the nuclei of atoms break apart in radioactivity?

Accepted Answer

The forces that bind protons and neutrons together in the nucleus (called nuclear forces) are strong, but they can become overwhelmed by repulsive forces between protons, especially in heavier elements. This can cause the nucleus to become unstable and break apart, resulting in radioactivity. None of the other choices describe the mechanism behind nuclear decay.

Question 4

Which era are we currently in?

Accepted Answer

We are currently in the Cenozoic era, which began around 66 million years ago and is known as the "Age of Mammals".

Question 5

The ________ period on the geologic time scale is a historic name that has now largely been replaced by the Paleogene and Neogene periods.

Accepted Answer

The Tertiary period was divided into the Paleogene and Neogene periods in 2004, with the Paleogene including the earlier part of the Tertiary and the Neogene including the later part. Therefore, the Tertiary period is no longer used as an official term on the geologic time scale.

Question 6

What is the half-life of potassium-40?

Accepted Answer

Potassium-40 has a half-life of approximately 1.3 billion years.

Question 7

What does "-zoic" in the eras of the geologic time scale refer to?

Accepted Answer

The suffix "-zoic" means "pertaining to life," as seen in the names of the eras such as Paleozoic, Mesozoic, and Cenozoic which are characterized by distinctive developments and diversification of life forms.

Question 8

A deposit of volcanic tuff contains the isotope potassium-40, which is slowly decaying into argon-40.How might the apparent age of the sample be affected if the volcanic tuff is heated and remains heated for a long period of time?

Accepted Answer

Heating the sample could release some of the argon-40, which could make the sample appear younger than it really is. This is because the amount of argon-40 present in the sample would be less than expected based on the amount of potassium-40 present.

Question 9

What materials are best dated with carbon-14?

Accepted Answer

Carbon-14 is used for dating organic materials such as wood, bones, and charcoal.

Question 10

What is the effective maximum range for carbon-14 dating?

Accepted Answer

The effective maximum range for carbon-14 dating is approximately 70,000 years. Beyond this time frame, there is not enough carbon-14 remaining in a sample to accurately determine its age.

Question 11

________ is a term used to define 88% of Earth's history prior to the start of the Paleozoic era.

Accepted Answer

The Precambrian is the term used to define 88% of Earth's history prior to the start of the Paleozoic era. The Quaternary, Paleogene, and Jurassic periods are all much younger and occurred during or after the Paleozoic era.

Question 12

Which two conditions are the most important in order for an organism to become fossilized?

Accepted Answer

Rapid burial is necessary to prevent scavenging and decay, while possession of hard parts (such as bones or shells) is necessary for preservation in the fossil record.

Question 13

If ²³⁵U has 92 protons, how many neutrons does it have?

Accepted Answer

The number after the element's symbol represents its Atomic Mass, which is the total number of protons and neutrons in an atom's nucleus. Therefore, if the atom has 92 protons, we need to find the number of neutrons that will add up to 143 to reach an atomic mass of 235. 
235 (atomic mass) - 92 (atomic number) = 143 (number of neutrons)

Question 14

You are trying to determine the age of a lava flow using an isotope with a half-life of 1.5 million years.If the sample has gone through four half-lives, what is the age of the rock?

Accepted Answer

Each half-life represents 1.5 million years, so four half-lives represent 6 million years. Therefore, the age of the rock is 6 million years.

Question 15

In what era is the Jurassic period?

Accepted Answer

The Jurassic period is part of the Mesozoic era, which spans from about 252 million years ago to 66 million years ago. It is characterized by the dominance of dinosaurs, as well as the emergence of other reptilian groups like pterosaurs and marine reptiles.

Question 16

Which particle of an atom will determine the atomic number of an element?

Accepted Answer

The atomic number of an element is determined by the number of protons in the nucleus. This is because each proton has a positive charge, and the number of protons in the nucleus determines the element's identity.

Question 17

What is a fossil assemblage?

Accepted Answer

A fossil assemblage is a group of fossils that are found together and can be used to determine the age of the rock unit they are found in. The types of fossils present in the assemblage can provide clues about the environment and conditions during that time period.

Question 18

You are an archaeologist researching artifacts left behind by Francisco Pizzaro's conquest of Peru in the 1530s.In order to confirm the authenticity of the leather artifacts, you are performing radiometric dating using an isotope pair that has a half-life of 250 years.In order for the artifacts to date back to the time of Pizzaro's conquest, approximately how much original radioactive isotope must be left in the artifacts?

Accepted Answer

Since the isotope pair has a half-life of 250 years, after 250 years, half of the original radioactive isotope will remain. Therefore, after 500 years, only 25% of the original radioactive isotope will remain, which means that the artifacts must have approximately 25% of the original radioactive isotope to date back to Pizzaro's conquest.

Question 19

What is an isotope?

Accepted Answer

Isotopes are atoms of the same element that have different numbers of neutrons. This means they still have the same number of protons (thus, the same atomic number) but varying atomic masses.

Question 20

________ is a technique where the decay rate of radioactive isotopes is measured and used to determine the age of a geologic material.

Accepted Answer

Radiometric dating is the technique of using the decay rate of radioactive isotopes to determine the age of a geologic material. This is done by measuring the amount of parent isotope and daughter isotope present in the material and using the known decay rate to calculate the age. Additionally, the concept of half-life (D) is central to radiometric dating, as it is the time it takes for half of the parent isotope to decay into the daughter isotope. Electron capture (A) and ion exchange (C) may play roles in some types of radiometric dating, but they are not the primary technique used.

Quiz 9: Geologic Time

A neutron is a combination of a(n) and a(n) .

What is the definition of a half-life?

For what reason might the nuclei of atoms break apart in radioactivity?

Which era are we currently in?

The ________ period on the geologic time scale is a historic name that has now largely been replaced by the Paleogene and Neogene periods.

What is the half-life of potassium-40?

What does "-zoic" in the eras of the geologic time scale refer to?

A deposit of volcanic tuff contains the isotope potassium-40, which is slowly decaying into argon-40.How might the apparent age of the sample be affected if the volcanic tuff is heated and remains heated for a long period of time?

What materials are best dated with carbon-14?

What is the effective maximum range for carbon-14 dating?

________ is a term used to define 88% of Earth's history prior to the start of the Paleozoic era.

Which two conditions are the most important in order for an organism to become fossilized?

If ²³⁵U has 92 protons, how many neutrons does it have?

You are trying to determine the age of a lava flow using an isotope with a half-life of 1.5 million years.If the sample has gone through four half-lives, what is the age of the rock?

In what era is the Jurassic period?

Which particle of an atom will determine the atomic number of an element?

What is a fossil assemblage?

What is an isotope?

________ is a technique where the decay rate of radioactive isotopes is measured and used to determine the age of a geologic material.

Quiz 9: Geologic Time

A neutron is a combination of a(n) ________ and a(n) ________.

What is the definition of a half-life?

For what reason might the nuclei of atoms break apart in radioactivity?

Which era are we currently in?

The ________ period on the geologic time scale is a historic name that has now largely been replaced by the Paleogene and Neogene periods.

What is the half-life of potassium-40?

What does "-zoic" in the eras of the geologic time scale refer to?

A deposit of volcanic tuff contains the isotope potassium-40, which is slowly decaying into argon-40.How might the apparent age of the sample be affected if the volcanic tuff is heated and remains heated for a long period of time?

What materials are best dated with carbon-14?

What is the effective maximum range for carbon-14 dating?

________ is a term used to define 88% of Earth's history prior to the start of the Paleozoic era.

Which two conditions are the most important in order for an organism to become fossilized?

If 235U has 92 protons, how many neutrons does it have?

You are trying to determine the age of a lava flow using an isotope with a half-life of 1.5 million years.If the sample has gone through four half-lives, what is the age of the rock?

In what era is the Jurassic period?

Which particle of an atom will determine the atomic number of an element?

What is a fossil assemblage?

What is an isotope?

________ is a technique where the decay rate of radioactive isotopes is measured and used to determine the age of a geologic material.

A neutron is a combination of a(n) and a(n) .

If ²³⁵U has 92 protons, how many neutrons does it have?