Atomic radius, crystal structure, electronegativity, and the most common valence are given in the following table for several elements; for those that are nonmetals, only atomic radii are indicated.

Which of these elements will be a solute (impurity) to form a substitutional solid solution with nickel as solvent (host)?

Which of these elements would you expect to form an interstitial solid solution with nickel as solvent.

Element	Atomic Radius (nm)	Crystal Structure	Electro-negativity	Valence
Ni	0.1246	FCC	1.8	+2
C	0.071
H	0.046
O	0.060
Ag	0.1445	FCC	1.4	+1
Al	0.1431	FCC	1.5	+3
Co	0.1253	HCP	1.7	+2
Cr	0.1249	BCC	1.6	+3
Fe	0.1241	BCC	1.7	+2
Pt	0.1387	FCC	1.5	+2
Zn	0.1332	HCP	1.7	+2