Label the following reaction as Synthesis or Decomposition Se+O_(2)arrow SeO_(3) Synthesis Decomposition

The given reaction is . In this reaction, selenium (Se) and oxygen (O_{2}) combine to form selenium trioxide (SeO_{3}). This is a synthesis reaction because two or more simple substances combine to form a more complex substance. In a synthesis reaction, the reactants may be elements or compounds, and the product is always a compound. The general form of a synthesis reaction is . In this case, selenium and oxygen are the reactants, and selenium trioxide is the product. Therefore, the reaction is a synthesis reaction.