how do you use the terms Electron Shielding Effect and Effective Nuclear Charge, to make a statement about atomic radius trends within a group AND period in the periodic table?

What is the composition, in atom percent, of an alloy that consists of 4.5 wt% pb and 95.5 wt% sn? the atomic weights for pb and sn are 207.19 g/mol and 118.71 g/mol, respectively.(a) 2.6 at% pb and 97.4 at% sn(b) 7.6 at% pb and 92.4 at% sn(c)97.4 at% pb and 2.6 at% sn(d) 92.4 at% pb and 7.6 at% sn

Your friend offers to show you an intrusive igneous rock. which of the following would you expect to see?

What is the percent by mass of oxygen in fe2o3