What percentage of Uranium 238 is left after 3 half lives?

Which of the following is true about fossils? a. the relative age of fossils cannot be determined from their position in sedimentary layers. b. fossils found in lower layers of sedimentary rock are as old as fossils found in upper layers of sedimentary rock. c. fossils found in upper layers of sedimentary rock are older than fossils found in lower layers of sedimentary rock. d. fossils found in lower layers of sedimentary rock are older than fossils found in upper layers of sedimentary rock.

How does a command economy differ from a mixed market economy? in a command economy, citizens have fewer property rights. in a mixed market economy, citizens have more property in a command economy, citizens have more property rights. in a mixed market economy, citizens have fewer property rights in a command economy citizens own all public property. in a mixed market economy, the government owns all private, property in a command economy, citizens own all private property in a mixed market economy, the goverment owns all public property

True or false. epeirogenic changes deform the crust.