Your school's website says a nursing degree requires 6 credits of humanities and a chemistry with an on campus lab (chem 100 meets that requirement). The chemistry has to be taken within the last five years. The chemistry has to be completed before you take nursing classes and the humanities can be done anytime. Technically, this makes the chemistry a prereq and technically the humanities are not prereqs, they are general ed classes. People tend to be loose about those terms. Perhaps your advisor was or perhaps you just didn't notice the difference.
It is possible the prof was using the technical definition. And the advisor was recommending you finishing the humanities off before the nursing classes so you can concentrate on the nursing classes when you take them even though you are allowed to take them with nursing classes. (I second that recommendation).
Other possibilities: it is possible you met the chemistry requirement with your high school chemistry class - if you took a beefy enough one ... and your advisor knows that because she can see all your records. The professor might just know that you told him you haven't taken a college chemistry. (speculating here).
Possibly one or the other had all the information and just had a bad day or a spacey moment and missed something or simply made a mistake.
Sometimes the requirements change and the school is slow to update their catalogs - but these are quite common as requirements - so that is unlikely.
If I were you, I was comb through the catalog and the nursing school
FAQs pages and list what requirements you have finished (with what class taken in which term for what grade). I would also make another advising appointment and ask him or her to show you the requirements and what from your record meets which requirement.