Final answer:
The chemical element most likely to be found in the formula of a base is OH (hydroxide), as in sodium hydroxide (NaOH), which is a common base.
Step-by-step explanation:
The element most likely to be found in the chemical formula of a base is OH (hydroxide). Bases can be defined as substances that accept protons from acids and commonly include hydroxide ions in their structure. A familiar example of a base is sodium hydroxide (NaOH), which is an ionic compound containing sodium (Na), oxygen (O), and hydrogen (H). The hydroxide ion (OH⁻) in such compounds accepts a proton (H⁺) from acids to form water (H₂O).