Answer:- Synthesis.
Explanations:- Two species are reacting to make a newer one and so it is an example of a synthesis reaction.
If an equation is of the type,
then it is called synthesis reaction.
The given reaction in the question is,
![P_4O_1_0+6H_2O\rightarrow 4H_3PO_4](https://img.qammunity.org/2020/formulas/chemistry/middle-school/ut5gtvo3pqtd79c6iqb4dt5n39h6as6rcc.png)
The above reaction looks exactly similar to the general equation we have written in the starting.
and water are reacting to form phosphoric acid and so it is a synthesis reaction.