Which of the following elements is the most reactive?

• A. Carbon
• B. Nickel
• C. Sodium
• D. Oxygen

Answer: (C)

Verified step by step guidance

1. Understand that reactivity in elements depends on their position in the periodic table and their tendency to lose, gain, or share electrons to achieve a stable electron configuration.
2. Recall that metals, especially alkali metals like Sodium, are highly reactive because they have a single electron in their outermost shell that they readily lose to form positive ions.
3. Compare the elements given: Carbon is a nonmetal with moderate reactivity, Nickel is a transition metal with relatively low reactivity, Oxygen is a nonmetal that is reactive but typically gains electrons rather than loses them.
4. Recognize that Sodium, an alkali metal, is the most reactive among the options because it easily loses its one valence electron to form Na⁺, making it highly reactive, especially with water and oxygen.
5. Conclude that Sodium's position in Group 1 of the periodic table and its electron configuration explain why it is more reactive than Carbon, Nickel, or Oxygen.