Why would pure iron not be suitable for a hip replacement joint

Because iron is an element meaning that it only contains iron atoms, pure iron is easily oxidized meaning that oxygen readily reacts with the surface of the iron which causes it to rust. since the iron joint replacement is surrounded by wet tissues would it would rust and flake off which could cause serious problems.

Yes she is correct. the answer is completely correct

Ch4 is nonpolar and insoluble in water. since all of the hydrogen atoms are evenly spread around the carbon atom even through the c h bond is polar all the poles cancel each other out.