tourists ask a lot of questions and a guide should be friend helpful, and approachable. Guides shouldn't claim to know everything we're not superhuman! if you don't know the answer, say so, but add I'll find out for you.
Questions can vary. They can be practical ones; it's important to know where the toilets are situated as well as the date of a monument! When things go wrong-as they occasionally do-a guide should pause and calmly sort out the problem, and try to make sure that the original itinerary is kept to.