The prefix iso- denotes which meaning?

• A. Similar
• B. Balance
• C. Like
• D. Equal

Answer: (D)

iso- signals equality or sameness in a property. In medical and scientific terms, it’s used to show two things share the same measure or characteristic: isometric means same size or length, isobaric means same pressure, isothermal means same temperature, isomorphic means same form. Therefore, the best match for iso- is equal. While similar and like describe resemblance, they don’t convey exact equality, and balance isn’t the sense the prefix carries. An isotope uses iso- to indicate same place in the element family (same atomic number) even though other properties differ.