For each of the metals listed in the table, compute the Pilling$-$Bedworth ratio. Also, on the basis of this value, specify whether or not you would expect the oxide scale that forms on the surface to be protective, and then justify your decision. Density data for both the metal and its oxide are also tabulated.

$\backslash$table$[[,\backslash$table$[[$Metal$],[$Density$],[($g$/$cm $($:${?}^3$