Please help chemistry

What is Ag+ and N3- as a formula together?

What is common about these molecules? a.their atoms are held together by covalent bonds. b.they are all made up of the same two atoms. c.their atoms are held together by ionic bonds. d.they are all made up of oxygen atoms only.

If a plot weight (in g) vs. volume (in ml) for a metal gave the equation y= 13.41x and r^2=0.9981 what is the density of the metal?

How many miles of water are produced if 5.43 mol pbo2 are consumed