For the first problem, the word waltzs is misspelled, as the plural of waltz is waltzes.
For the second problem, the word obnoxious gives Jack's behavior the most negative connotation.
For the third problem, the answer is skillful, because the sentence tells the reader that complex tasks are easy for her.
For the fourth problem, crisis is the irregular noun that is misspelled, as the plural of crisis is actually crises.
For the fifth problem, the answer is firefighter : hose, because a plumber uses a wrench to complete his work, as a firefighter similarly uses a hose.
For the last problem, the prefix is ex-, which creates the word except, the only word that fits the meaning stated in the problem.
Hope this helps!