Why is "chance" plural here? Can't I say "What is the change of ~"?
"Chance" and "chances" are both used to talk about possibility. However, "chance" is also used to talk about opportunity. Because of this "chances" is generally a lot more common than "chance", even when only one possibility is being talked about, which is the case here. Ex: There is a chance that she will be able to carry the Olympic torch. (possibility) Ex: Chances are she will be able to carry the Olympic torch. (possibility) The first example is talking about something that it is known will happen or be possible. The second example is talking about a hypothetical outcome. Ex: She had the chance to carry the Olympic torch. (opportunity)