Because there are 2 oxygen atoms on the reactants side and only one on the products side. You can either add a coefficient of 1/2 on the O2 or you can add a coefficient of 2 on H2 and H2O.
H2O + Ca ----> H2 + CaO
Ca + 2H2O ==> Ca(OH)2 + H2
The chemical reaction is:SO2 + 2 H2 = 2 H2O + S
O + h2 = h2o
HCl + NaOH = H2O + NaCl is already balanced.
No. It would have to be H2O2 - H2 = O2 in order to be balanced.
H2O + Ca ----> H2 + CaO
Ca + 2H2O ==> Ca(OH)2 + H2
The chemical reaction is:SO2 + 2 H2 = 2 H2O + S
O + h2 = h2o
Sr + 2 H2O -> Sr(OH)2 + H2
HCl + NaOH = H2O + NaCl is already balanced.
The chemical equation is:2 H2 + O2 = 2 H2O
Balanced :2 K + 2 H2O ----> 2 KOH + H2
The answer as stated in the question is wrong which is why it can not be balanced. To balance Ca + 2H20 -------> Ca(OH)2 + H2 check on the related link.
What information can you determine from the coefficients in this balanced chemical equation? Mg + 2HCl → MgCl2 + H2
H2 +o2 --->h2o