Which of the following statement(s) is/are correct?

Industrially, $O_2$  is obtained from air by first removing $C{O}_2$  and water vapour and then, the remaining gases are liquefied and fractionally distilled to give $N_{2}and{O}_2$  

$O_2$ directly readily reacts with Au and Pt 

Roasting of iron pyrites gives $F{e}_2{O}_{3}andS{O}_2$

Both $C{O}_{2}andS{O}_2$ readily decolourises acidified potassium permanganate (VII) solution