Short answer: it depends on how the Core test will count.
EPA’s certification requirements page acknowledges Core tests taken as an open-book exam, but says an open-book Core test cannot be used to get Universal certification. To attain Universal, the Core test must be proctored.
That is the important nuance: an open-book Core result is not interchangeable with the proctored Core test required for Universal. If you are testing toward Universal, ask the EPA-approved certifying organization how it will administer your Core test before you begin.
Read the rule on the EPA Section 608 Technician Certification Requirements page.
Use the testing organization’s instructions for the details.
EPA requires tests for Section 608 certification to be administered by an EPA-approved certifying organization. The EPA rule describes the Universal Core requirement; your certifying organization provides the specific appointment, materials, and testing instructions for its exam process.
EPA lists four certification types: Type I for small appliances, Type II for high- or very high-pressure appliances (with small appliances and MVACs excepted), Type III for low-pressure appliances, and Universal for all types of equipment. The test topics vary by type, so avoid assuming that one description of exam format applies to every candidate or provider.
The EPA test-topic list is a study guide to subject areas; it is not a statement that test forms are identical nationwide.
A note for apprentices
EPA says apprentices are exempt from certification requirements while they are closely and continually supervised by a certified technician. An apprentice who meets that condition is not the same as an unsupervised technician working without certification.
Brassleaf’s practice material is for study. It is not an EPA-approved certification test, and it does not determine which format your certifying organization will use.