if the U-235;Pb-207 ratio in a zircon crystal in a sandstone was found to be 1:3 how old is the zircon.

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.

Consider the following multistep reaction: a b→ab(slow) a ab→a2b(fast)−−−−−−−−−−−−−−−−− 2a b→a2b(overall) based on this mechanism, determine the rate law for the overall reaction. express your answer in standard masteringchemistry format. for example, if the rate law is k[a]3[b]2 type k*[a]^3*[b]^2

Which proportionality applies to avogadro’s law?