H2 + 02 h2o

subscript:

coefficient :

reactant :

product:

all reactants and products must be identified through chemical analysis. 2. ... Coefficients are added when necessary a small whole ... NEVER change the subscripts***. H2O (l) H2 (g) + O2 (g) reactants products. H. O. H. O.

Explanation:

  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-