Which reactions are redox reactions? check all that apply. check all that apply. 4li(s)+o2(g)→2li2o(s) mg(s)+fe2+(aq)→mg2+(aq)+fe(s) pb(no3)2(aq)+na2s?

The reaction s that are redox reactions are

4Li(s) +O2 (g)→ 2Li2O (s)\

Mg(s) +  Fe2+ (aq)→ Mg2+(aq) + Fe(s)

A redox reaction involve both oxidation and reduction. During redox reaction there is change in oxidation states. For example in

4Li +O2 →2Li2O  Li is oxidized  while O  is  reduced

in  Mg +Fe2+ → Mg2+ +Fe   Mg is oxidized since it move from oxidation state 0 to 2+ while Fe2+ is reduced since it move from oxidation state of 2+ to 0