I'm a junior in high school, I sent in a application to New York Presbyterian Hospital for a summer volunteer job, and I got a call saying that they wishes to interview me. Can anyone tell me what they might ask? What should I wear? I'm very nervous! But this is something I really would like to do.
I rotated at Weil Cornell during my clinicals at respiratory school. We were required to wear slacks, buttoned shirt, and tie (with lab coat, but that's not applicable to you of course). In my experience, it's always better to up-dress, you can never go wrong that way. If you have a suit, perfect. If not, do the slacks/shirt/tie (and make sure you're not wearing tennis shoes or something). This has no bearing on what you might wear while volunteering, just in case you're worried about that.
I think what they might ask depends on what you're volunteering for. But I'd guess they just want to see who you are and see if you're presentable and not some nut. I'd just go in expecting to answer questions about myself, be prepared to explain your past, present, and future goals. Do a little online research of the hospital (their web site works), this is another of those things that you can never go wrong with, in case they ask "what you know about the place" or the department you're planning to volunteer for (and why you want to volunteer in that department/hospital).