Examine the following half-reactions and select the strongest oxidizing agent among the species listed. Cr2+(aq) + 2e– LaTeX: \longrightarrow⟶Cr(s) E° = –0.913 V Fe2+(aq) + 2e– LaTeX: \longrightarrow⟶ Fe(s) E° = –0.447 V Sr2+(aq) + 2e– LaTeX: \longrightarrow⟶ Sr(s) E° = –2.89 V Co2+(aq) + 2e– LaTeX: \longrightarrow⟶ Co(s) E° = –0.28 V

  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-

particle   p is an electron and particle q is a neutron

elements make up everything, and they combine to make compounds.

the answer is c

answerca air mass;