Uranium-235 (u-235) radioactively decays into lead-207 (pb-207). if i'm measuring the number of atoms in a mineral, and i find that there are 1000 atoms of u-235 and 3000 atoms of pb-207, then how many atoms of these elements were in the mineral when the rock first formed?

Which of the following insects is a decomposer? a. mosquito. b. caterpillar. c. beetle. d. none of the above.

Aplane cuts a pyramid as shown in the diagram. what is the shape of the cross section? a. a hexagon b. a pentagon c. a square d. a triangle

What is the difference between the cultures of central asia and the caucasus region? the majority of people in central asia are muslim; the majority in the caucasus region are christian. the primary language in central asia is armenian; the primary language in the caucasus region is russian. central asia has been plagued by ethnic unrest; the caucasus region has had little ethnic conflict. the effects of soviet rule can still be seen in central asia; the caucasus region has developed its own identity since the fall of the ussr.