The given reaction is double displacement reaction. In this reaction arsenic trichloride and hydrogen sulfide react and produced arsenic sulfide and hydrogen chloride. In double displacement reaction both anion an cation of reactants are exchanged with each other.
Double replacement:
It is the reaction in which two compound exchange their ions and form new compounds.
There are no states in the picture, but Na should have a "(s)" after it, and Cl2 should have a "(g)" after it. NaCl should have an "(s)". Chlorine is a diatomic element so it has a "2" subscript on it.
