Here's why:

* Electrochemical Series: Sodium (Na) is higher in the electrochemical series than zinc (Zn). This means that sodium has a greater tendency to lose electrons and form positive ions, making it a more reactive metal.

* Reactivity with Water: Sodium reacts vigorously with water, releasing hydrogen gas and heat. Zinc reacts much more slowly with water, and only at elevated temperatures.

* Reactivity with Acids: Sodium reacts violently with acids, producing hydrogen gas. Zinc reacts with acids, but the reaction is less vigorous.

In summary: Sodium's higher position in the electrochemical series, its vigorous reactions with water and acids, and its general tendency to lose electrons all point to its greater reactivity compared to zinc.