Which of the following are valid contracts? Which of the following are not valid contracts? Explain why.

1. Megatron points a gun at Optimus Prime and tells him to sign a contract agreeing to deflate Bumblebee's tires. Optimus Prime signs the contract.
2. Rainbow Dash offers to pay Applejack $25 to bake an apple pie. Applejack doesn't reply.
3. Rainbow Dash offers to pay Applejack $25 to bake an apple pie. Applejack says she'll bake the pie for $50.
4. Before Woody and BoPeep get married, they agree in writing that if they divorce that Woody will get custody of Bullseye.
5. Scar and Simba (age 3) sign a contract stating that Simba will give up his throne for Scar.
6. Marlin and Dory sign a contract agreeing they will work together to find Nemo. Dory does not disclose that she has short term memory loss to Marlin before they sign the contract.
7. After being hypnotized by Jafar, the Sultan of Agrabah signs a contract with Jafar that says Jafar will be able to marry Jasmine.
8. The Sultan of Agrabah signs a contract with Aladdin that says Aladdin will be the next sultan because Aladdin says he is actually Prince Ababwa.
9. Darth Vader and Emperor Palpatine sign a contract wherein Darth Vader agrees to kill Luke Skywalker in consideration for more power.
10. Rapunzel and Flynn Rider sign a contract wherein Flynn will take Rapunzel to see the floating lanterns in exchange for Rapunzel giving Flynn the satchel with the crown.