Ellingham diagram is the plot of $X$ vs $Y$, what are $X$ and $Y$ ?

$$ \text { Match the following. } $$

$$ \begin{array}{llll} \hline & \begin{array}{c} \text { List-I } \\ \text { (Refining method) } \end{array} & & \begin{array}{c} \text { List-II } \\ \text { (Metals to be refined) } \end{array} \\ \hline \text { (A) } & \text { Zone refining } & \text { (I) } & \text { Titanium } \\ \hline \text { (B) } & \text { Poling } & \text { (II) } & \text { Tin } \\ \hline \text { (C) } & \text { Liquation } & \text { (III) } & \text { Gallium } \\ \hline \text { (D) } & \text { Vapour phase refining } & \text { (IV) } & \text { Copper } \\ \hline \end{array} $$

The correct answer is

Sphalerite, siderite and malachite are the ores of metals $X, Y$ and $Z$. The atomic numbers of them are respectively

Which element does not exist in elemental state in the earth's crust?