If 0.33 moles of sulfuric acid were consumed in the reaction, how many
moles of ammonium hydroxide would be required?

Sulfurous acid is formed by the reaction of water and sulfur dioxide.

Balanced reaction will provide the basic information.

Balanced Reaction :

                         SO₂ +  H₂O > H₂SO₃

                        1 mol    1mol                  1mol

From above reaction we come to know

1 mole of H₂O ≅ 1 mole H₂SO₃

if 1 mole of H₂O produces 1 mole of H₂SO₃ then

0.680 mole of water will be required to produces sulfurous acid

Explanation through calculation

apply the unity formula

1 mole of the H₂O ≅ 1 mole of H₂SO₃

x mole of the H₂O ≅  0.680 moles of H₂SO₃

so by cross multiplication

1 mole  x X mole ≅ 1 mole  x 0.680 mole

we have to find moles of H₂O so by rearrangement of the above equation

X mole of H₂O = 1 mole x 0.680 mole

X mole of H₂O =  0.680 moles

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-