please answer all the question. avoid plagarism.

thank you

1st question. Provide three examples of software projects that would be amenable to the prototyping model. Be specific.

2nd question. As you move outward along the spiral process flow, what can you say about the software that is being developed or maintained?

3rd question;It is possible to prove that a software component and even an entire program is correct. So why doesn't everyone do this?