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?

Why might have people followed the rivers to find their way into asia

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

Which was not a country that massively built up its navy in the early 1900s? germany china united statesbritain