Which of the following are contracts? If not, please explain which element(s) is defective.

1. The Captain agrees to sell Tennille Blackacre for $400 based on the description of the property found in county records. The Captain and Tennille later discover that the description is incorrect and that Blackacre is really half the size they thought. Is Tennille still obligated to buy Blackacre for $400?
2. You fill out an employment application indicating that you are an experienced widget maker, but, in fact, you have never made a widget in your life. Based on your "experience," Widgets, Inc. hires you as the supervisor of widget production. You are performing your job with no apparent difficulty when your boss discovers the truth about your previous level of experience and fires you. Do you have an enforceable contract with Widgets, Inc.?
3. Gertrude (grandmother) is elderly and housebound. Her housekeeper/nurse, upon whom she is very dependent, tells Gertrude that if she does not make her the beneficiary in her will, she will stop helping her. Gertrude agrees. Does Gertrude have a contract with her housekeeper?