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

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

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?

Which one of the following statements is true about the froth flotation method?