Unscored items on the ATI TEAS exam are questions that ATI is testing for student performance before introducing them on an actual proctored exam.
The ATI TEAS consists of 170 total questions and 150 are scored while 20 are unscored. Unscored items (test questions) do not count towards your final TEAS score but do provide useful information on the quality and relative difficulty of the questions. If a question is too hard or too easy, it will be reworked and resubmitted.
How can you tell if a test question is scored or unscored? You can't. And that's the point. If you knew which questions didn't count toward your final score, you probably wouldn't answer them and we wouldn't get the data we need to improve the questions.