Final answer:
A) Sodium and Chlorine The most vigorous reaction would occur between sodium and chlorine, which are highly reactive metal and halogen, respectively.
Step-by-step explanation:
The question asks which pair of elements would react together most vigorously. Among the given options, sodium and chlorine would react most vigorously.
Sodium is a highly reactive metal that can react explosively with water, while chlorine is a corrosive, yellow-green gas. When combined, they undergo a vigorous reaction to form sodium chloride, also known as table salt.
This reaction is exothermic and releases a large amount of energy, showing the strong reactivity between a highly reactive metal and a halogen.
As reference, zinc metal reacting with hydrochloric acid and sodium reacting with water are examples of single-displacement and highly exothermic reactions, respectively.
However, neither of these reactions is as vigorous as the combination of sodium and chlorine. The reaction between iron and copper is not as vigorous as they are both metals and do not tend to react with each other.
Hydrogen and helium will not react at all, as helium is a noble gas and is inert. Therefore, the correct answer to the question is A) Sodium and Chlorine.