As I've worked with more different languages over my career, I've become less and less able to answer those syntax / standard-library questions, simply because there are so many half conflicting memories of other ways to do it.

If the interviewer is any good--big if--they'll mainly be concerned about whether the candidate is making plausible code, regardless of whether it is String.split(s1,s2) or s1.split(s2) or StringUtil.split(s2,s1) ...