If oxygen is removed from a sample of air as iron rust, what happens to the particle pressure of oxygen in the air?

Answer : It increases

Rusting is where oxygen binds to iron and forms iron oxide.

So once iron rusts, there is oxygen, just not in air; it's in the iron oxide.

All reactions are reversible, albeit at different rates (the "irreversible" ones are still reversible, but much slower given that they take so much collision luck and energy.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

6.4 cm (max) - 25 cm (min)