"Num urbs Novum Eboracum in California est?"
Translation:Surely the city of New York is not in California?
The accent is very anglosaxon so difficults comprehesion. You may not appreciate that nuance, but sounds like barbarians speaking Latin. The spoken parts should be done by either Spanish or Italian people, even Portuguese people, who are related phonetically and grammatically to Latin. However I don't want to wrest merit to you, guys. You did outstandingly very well. Congrats!
Because when a sentence begins with Num it means the speaker is expecting the answer to be negative. It does not need the negative non but you need to translate it as such. This is explained in the tips section. I'd recommend looking over it to help you understand it better :)
"Californiae" would be the locative, which exists only for names of cities and small islands (plus a handful of common nouns like "domus"). Since "California" is neither one nor the other but the name of a state, you can not use locative case for that word.
Instead, since you are talking about a place where the "action" is taking place without movement involved, you use the following construction: preposition "in" + noun in the ablative case.