is it possible to tell if this film was ever used
A roll of 35mm film that has
been exposed in a camera generally has 4 sprocket holes exposed on the short side of the leader. If it was in a camera and rewound, more or less than 4 sprocket holes will be exposed. I say in general because I'm sure some film, somewhere, has left the factory with more or less than 4 holes exposed, although I've never seen one. We've been processing 35mm film for 13 years and I never saw a NEW roll that didn't have 4 holes exposed.
It would normally be viewed with a "Slide Projector", a "Slide Viewer" or on a "Light Table".
nikkormat, you do realize these posts you are digging up are over a year old, right?