volvieras

So i applied to 11 masters and phd programs (about half for each) one of my programs has accepted me and has told me i need to notify them of acceptance by april 15th, yet i haven't even had replies back from more than half of my other programs... Am i allowed to accept the schools invitation and then not show up? what, if any, are the repercussions behind this? has anyone been in this situation before? how did you handle it? any advice would be great, thanks in advance!