I have 3 questions that I am uncertain about.

Question

1) what determines the order in which the coumponent elements of binary molecular compounds are written?
2) Name the Binary compound according to the prefix system for As2O5
3) write the formula for each of the binary compound for tetraphosphorus decoxide.

Answer 1

1. Usually the cation (more electropositive element) is named first followed by the anion (more electronegative element).

2. diarsenic pentoxide

3. P₄O₁₀
but I don't understand the EACH OF THE....There is only one compound here. Unless you want the equation.
P4 + 5O2 ==> P4O10