Final answer:
The chemical reaction 16Na(s) + S8(g) = 8Na2S(s) is classified as a combination reaction, as two reactants combine to form a single new product.
Step-by-step explanation:
The chemical reaction given is 16Na(s) + S8(g) = 8Na2S(s). This reaction can be classified based on the process that the reactants undergo. In this reaction, solid sodium (Na) and sulfur gas (S8) combine to form solid sodium sulfide (Na2S). According to the classification of chemical reactions, when elements or compounds react to form a single new substance, the process is known as a combination reaction or a synthesis reaction. The given reaction has two reactants combining to form one product, which is typical of a combination reaction.
Therefore, the classification for the reaction 16Na(s) + S8(g) = 8Na2S(s) is D. Combination.