AST 113 - homework 5

In a sample that is one billion years old, which of the following should still be present in the sample today at more than 50% of the amount that was in the sample one billion years ago? a. radioactive isotopes with half-lives of one hundred billion years b. radioactive isotopes with half-lives of half a billion years c. radioactive isotopes with half-lives of one million years d. radioactive isotopes with half-lives of a few thousand years

a. radioactive isotopes with half-lives of one hundred billion years

Based on what we have covered in class so far, what current methods do we have for investigating how the Sun formed? a. telescopic observations of other stars currently forming b. the development of the physics involved in forming stars c. obtaining a sample of the outer layers of the Sun d. observing the Sun when it formed e. both A and B

a. telescopic observations of other stars currently forming

This article discusses early history of the Solar System. In the description of how we think the Solar System formed, for what part of that history does the author not describe lines of evidence? a. the formation of the Sun b. early bombardment of the Moon c. early bombardment of the Earth d. changes in orbits of the outer Solar System planets

a. the formation of the Sun

What is the relative timing of when this potassium in the lunar rock samples would have formed? a. likely pre-Milk Way Galaxy b. likely pre-Sun c. likely after the planets (and Earth's Moon) formed d. likely after impacts on the surface of the Moon e. likely after the rock on the Moon solidified following an impact

b. likely pre-Sun

The article mentions age dating lunar rock samples using the ratio between potassium-40 (the radioactive isotope) and argon-40 (the stable decay product). Based on what we have covered in class, the potassium that was incorporated into a rock on the Moon would have been formed by: a. the Sun b. a low mass, main sequence star like the Sun c. a higher mass star than the Sun that exploded d. the Big Bang in the early universe

c. a higher mass star than the Sun that exploded

These lunar rock samples would have formed... a. at the same time as the potassium isotope formed b. before the potassium isotope formed c. after the potassium isotope formed d. at an unknown time relative to the potassium isotope

c. after the potassium isotope formed

Estimating how old something is using radiometric age dating involves taking the ratio between the abundance of a radioactive isotope of an element and the abundance of the stable decay product of that isotope. The time it takes for half the amount of the unstable isotope to decay into the stable product is called the half-life; this half-life is different for different isotopes and is measured in the lab (meaning scientists have already accurately measured the half life of these isotopes). So by measuring how much of the unstable isotope with a known half-life remains in a sample relative to the amount of stable decay product, we can estimate the age of the sample. If we wanted to age date a sample that is potentially a few billion years old, what kind of radioactive isotope in the sample would we want to use to get the most accurate estimate of the sample's age? a. an isotope with a half-life of a hundred years b. an isotope with a half-life of a thousand years c. an isotope with a half-life of a billion years d. an isotope with a half-life of one hundred billion years

c. an isotope with a half-life of a billion years

What was the debate among scientists in the article? a. how valid the method of radiometeric age dating is b. whether most current methods of investigating the early solar system are valid c. whether recent, more detailed data using the current set of methods still supports the scientific community's ideas of the early history of the Solar System d. whether recent, more detailed data using a completely new set of methods still supports the scientific community's ideas of the early history of the Solar System

c. whether recent, more detailed data using the current set of methods still supports the scientific community's ideas of the early history of the Solar System

What kind of article is this and what kind of source is the article from? You may need to do some internet searches on what kind of source Nature is. a. a scientific paper; a scientific journal b. a summary of a scientific paper; a scientific journal c. an opinion piece about a group of scientific findings; a newspaper d. a summary and interpretive piece about a group of scientific findings; a scientific journal

d. a summary and interpretive piece about a group of scientific findings; a scientific journal

By getting an age from the potassium-argon ratio in a rock collected from the Moon, what timescale are we measuring? a. the time since the Sun formed b. the time since the Moon formed c. the time since the Earth formed d. the time since the rock on the Moon solidified

d. the time since the rock on the Moon solidified