4. thinking critically applying concepts
balance the following chemical equations by
adding coefficients:
a. hci + naoh + h2o + nacl
b. fe2o3 + c → fe + co2
c. so2 + o2 → so3

a. HCI + NaOH ---> H2O + NaCl

b. 2Fe2O3 + 3C → 4Fe + 3CO2

C. 2SO2 + O2 → 2SO3

  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-

i believe the answer is true.