Explain why ionic compounds are "fixed" in their chemical composition

Note the ph and poh values labeled with letters on the ph scale below. based on log rules and the way ph is calculated, what is the difference in [oh– ] concentration between point a and point b. a) 10^1 b) 10^5 c) 10^6 d) 10^7

Nickel crystallizes in the face-centered cubic (fcc) lattice. the density of the metal is 8902 kg/m3. calculate the radius of a nickel atom.

When the earth was formed and cooled, why did nickel and iron end up in the center of the earth while basalt and granite ended up in the outer layers