posted by Ramesh Reddy .
p2o5+H2o = H2P2O6
why is it H3po4? instead of H2P2O6 please explain me
You appear to be trying to use the reactants and simply sum them to find the product. That is what is wrong.
For example, Na + Cl2 ==> is not NaCl2 but NaCl. When Na combines with Na, the result is NaCl because Na has a valence of +1 and Cl has a valence of -1 therefore the formula is NaCl. You take care of making the atoms equal by balancing the equation.
Na + Cl2 ==> NaCl and we balance it like this.
2Na + Cl2 ==> 2NaCl.
K2O + H2O ==> is not K2H2O2 but KOH. We balance it as this.
K2O + H2O ==> 2KOH