$$ \text { Which of the following sets are correctly matched? } $$

$$ \begin{array}{cll} \hline & \text { Metal } & \text { Refining Process } \\ \hline \text { I. } & \mathrm{Hg} & \text { Distillation } \\ \hline \text { II. } & \mathrm{Cu} & \text { Poling } \\ \hline \text { III. } & \mathrm{B} & \text { Zone refining } \\ \hline \text { IV. } & \mathrm{Ti} & \text { Liquation } \\ \hline \end{array} $$

Kaolinite, a form of clay is the ore of metal $x$ and malachite is the ore of metal $y, x$ and $y$ respectively are

The alloy that contains copper and Zn is $x$ and the one that contains copper and Ni is $y$. What are $x$ and $y$ respectively?