It looks like you're looking for a word to fill in the blank in the sentence, which describes the reaction of students to a bad smell coming from the science lab. The most appropriate word to complete the sentence is "waft."
So the completed sentence would read:
"Something was going terribly wrong in the science lab, and the smell was beginning to waft to the other classrooms on the hall."
If you meant to select from a specific list of options, please provide that list, and I'll help you pick the correct answer!