VA group elements form tri oxides and pentoxides of the type `M_(2)O_(3)` and `M_(2)O_(5)` respectively (M-VA group element). The trioxides and pentoxides of nitrogen are monomers and that of P,As,Sb are dimers. Nitrogen forms various oxides ranging from `NO` to `N_(2)O_(5)`. Oxides of phosphorous have cage like stuctures.
Number of P-O-P bonds in `P_(4)O_(10)`:

Explanation

Number of P-O-bonds : 6