Final answer:
The boundary of an electron orbital is typically represented as enclosing a 90% probability of finding an electron, making the statement true.
Step-by-step explanation:
The question revolves around the shape of an electron orbital, which is the region around an atom's nucleus where electrons are most likely to be found. Contrary to the statement in the question, orbitals are typically depicted as enclosing a 90% probability, meaning that there is a 90% chance of finding an electron within the boundary defined. In reality, electrons exhibit quantum behavior, meaning they don't have a definite location but rather a probability distribution of where they might be at any given time. The boundary of an atomic orbital is usually termed in a manner that there is a 90% chance of finding an electron within that volume. Therefore, as represented in educational materials and scientific figures, the boundary of an orbital encloses the volume within which the electron is found with 90% probability, making the correct answer to the student's question (a) true.