Final answer:
The reaction 2H+ + 2Cl− → 2HCl is an example of a synthesis reaction, where simpler substances combine to form a single product, which in this case is hydrogen chloride (HCl).
Step-by-step explanation:
The reaction type for 2H+ + 2Cl− → 2HCl is a synthesis, which is option (a). This is because two simpler substances, hydrogen ions (H+) and chloride ions (Cl−), are combining to form a more complex substance, hydrogen chloride (HCl). A synthesis reaction is a type of chemical reaction where two or more substances combine to form a single product.
For context, another example of a synthesis reaction is H2 + Cl2 → 2HCl, where diatomic hydrogen and chlorine gases react to form hydrogen chloride gas. In contrast, an example that is not a synthesis reaction is the reaction between hydrogen bromide and chlorine to produce hydrogen chloride and bromine (2HBr + Cl2 → 2HCl + Br2).