What can scientists learn from the rate at which radioactive elements decay?
A. a rock's absolute age*
B. the relative age of rock layers
C. where one soil horizon ends and the next begins
D. the difference between molds and casts.
After six half-lives, what percentage of a radioactive sample will remain?
A. 0%-1%
B. 1%-3%*
C. 3%-6%
D. 6%-10%
Earth's oceans, atmosphere, and continents began to form during the first several hundred years of Precambrian time.
A. True*
B. False
A mold forms when minerals replace all or part of an organism.
A. True
B. False*
Your correct on all of them
What can scientists learn from the rate at which radioactive elements decay?
The answer to the question is A. a rock's absolute age. Scientists can use the rate at which radioactive elements decay to determine the age of rocks or other materials. This process is called radiometric dating. By measuring the amount of a radioactive element (parent isotope) and its decay product (daughter isotope) in a sample, scientists can calculate how long it has been since the rock or material formed. The decay rate is constant for each radioactive element, making it a reliable method for determining absolute age.
After six half-lives, what percentage of a radioactive sample will remain?
The answer to the question is B. 1%-3%. In radioactive decay, each half-life represents the amount of time it takes for half of the radioactive atoms in a sample to decay. After six half-lives, only a small fraction of the original radioactive sample remains. To calculate the remaining percentage, we need to use the formula (1/2)^(number of half-lives). For six half-lives, the calculation would be (1/2)^6 = 1/64 ≈ 1.56%. Therefore, the closest answer choice is B. 1%-3%.
Earth's oceans, atmosphere, and continents began to form during the first several hundred years of Precambrian time.
The answer to the question is A. True. Precambrian time refers to the earliest part of Earth's history, which lasted for about 4 billion years. During this time, the formation of Earth's oceans, atmosphere, and continents took place. The process of plate tectonics, volcanic activity, and the accumulation of gases from volcanic eruptions contributed to the formation of these features.
A mold forms when minerals replace all or part of an organism.
The answer to the question is B. False. A mold is a type of fossil that forms when an organism decomposes or dissolves, leaving behind an empty space in the shape of the organism. It does not involve the replacement of minerals. On the other hand, a cast forms when minerals fill in the mold, creating a replica of the original organism. So, a mold does not involve mineral replacement, making the statement false.