What is blister copper?

Which method is used for the purification of $Ni$?

Steel becomes soft and pliable by:

The reaction representing the $Mond$ process for metal refining is $............$.

Blister copper is refined by stirring molten impure metal with green logs of wood because such wood liberates hydrocarbon gases (like $CH_4$). This process $X$ is called . . . . . . . . . and the metal contains impurities of $Y$ is . . . . . . . . .

$TiI_{4}$ on heating gives