Question

Why in this equation oxygen became 5 . Pls answer this

Answer 1

before the reaction it was 5O2 which makes 5×2=10 and after the reaction it was written2P2O5 which means 2 is multiplied with both P2 and O5 when it is done.So 2×5 =10 as u can see before the reaction there were 10 atoms of oxygen and after the reaction there are also 10 atoms of oxygen. so the equation is balanced

Answer 2

In this equation we put 5 with O because we have to balance the equation by the method of valancy for example 2h+o2=2h2o.