Choose the most reactive metal from the options given below.

Sodium 

The correct answer is option 3. Sodium.

Out of the listed options, Sodium (option 3) is the most reactive metal.

Here's why:

Reactivity refers to a metal's tendency to lose electrons and form positively charged ions (cations) during reactions.

Sodium belongs to the group 1 alkali metals in the periodic table. Alkali metals are known for their high reactivity due to their single valence electron, which they readily lose to achieve a stable configuration.

Copper, Zinc, and Iron are all less reactive than sodium. They belong to different groups (12, 12, and 8, respectively) and have varying tendencies to lose electrons.

Therefore, based on their positions in the periodic table and their inherent properties, sodium is the most reactive metal among the given options.