Final answer:
Sodium, a very reactive metal, and chlorine, a poisonous gas, when combined, form sodium chloride (NaCl), also known as table salt. This reaction produces a safe and widely used compound from two hazardous elements.
Step-by-step explanation:
From the list provided, the element you would choose is sodium (Na). Sodium is a very reactive metal that, in isolation, can react with substances such as sweat to form sodium hydroxide, a corrosive substance. Conversely, chlorine (Cl), which is a pale yellow, poisonous gas, is very reactive as well. When these two elements are combined, they form the compound sodium chloride (NaCl), which is commonly known as table salt. This compound is a staple condiment and preservative used in cooking.
Sodium chloride forms as a result of an ionic reaction:
2 Na(s) + Cl₂ (g) → 2 NaCl(s).
This reaction between solid sodium and gaseous chlorine yields solid sodium chloride, illustrating the transformation of two hazardous elements into a stable compound suitable for consumption and various other applications.