Answer
W - Good conductor, malleable, high melting point, non reactive = Gold
X - Poor conductor, shatters into pieces (brittle), high melting point, reactive = Lead Sulfide
Y - Poor conductor, smashes into powder (brittle), low melting point with sublimation, non-reactive = Iodine
Z - Poor conductor, cracked, so very hard, high melting point, non-reactive = Quartz ($SiO_{2}$)
Work Step by Step
W - Good conductor, malleable, high melting point, non reactive = Gold
X - Poor conductor, shatters into pieces (brittle), high melting point, reactive = Lead Sulfide
Y - Poor conductor, smashes into powder (brittle), low melting point with sublimation, non-reactive = Iodine
Z - Poor conductor, cracked, so very hard, high melting point, non-reactive = Quartz ($SiO_{2}$)
