please correct my answers

Fill the blank with suitable clause and also put punctuation where necessary.

1. Mary wants a car which is affordable.
2. NSW University is an open university where everyone is welcomed.
3. We need a leader whom has a unique character.
4. Don’t trust anyone who you have just met.
5. A person who violates the law has to deal with the consequence.
6. The room was filled with flowers which were ordered by Jen.
7. Mr. Peterson, whom lives in our neighborhood, is a famous lawyer.
8. The red purse which my sister bought is quite expensive.
9. Songkran Festival, when there is water splashing everywhere, is Thai New Year.
10. Pete, whose wife is a superstar, used to be the top-seeded tennis player.

could you please explain what's wrong with the answers? and please give me the example of the right ones.

thank you so much :]

These are wrong (some just need commas):

1. NSW University is an open university, where everyone is welcomed.
2. We need a leader whom we can count on.
3. Don’t trust anyone who is a stranger.
   
4. The room was filled with flowers which were given for Jen.
5. Mr. Peterson, whom we met last night, is a famous lawyer.

correct?