Step1 firstly balance the Phophorous atoms by multiplying Right hand side by 4 Step 2 now balance oxygen atoms by multiplying H2O by 6 Step3 P4O10 +6 H2O-------> 4H3PO4 Solution Step1 firstly balance the Phophorous atoms by multiplying Right hand side by 4 Step 2 now balance oxygen atoms by multiplying H2O by 6 Step3 P4O10 +6 H2O-------> 4H3PO4.