Below are some case situations on CONTRACTS. Can you answer them? (with explanation or give some related article if possible)

1.Marco offered to sell Bruno a particular car for $10,000. Before Bruno could consent, Marco withdrew the offer. Was Marco allowed to do so?

2. Anna went to a store and offered to buy a certain phone for $1,000. The seller said he was willing to give it for $1,200. So, Anna turned to go away because he did not want to pay that price. The seller called her back and said he was willing to sell the phone for $1,000. Is Anna allowed not to buy said phone?

3. Alex offered 20 phone cases to Bela for $100 each. Bella answered by letter that she was willing to purchase 30 phone cases at said price at $100 each. Is the contract perfected?

4. John offered on May 1. Baxia accepted on May 8. The letter of acceptance was received by John on May 15. But on May 12, Baxia had already written a letter revoking the acceptance. Was there a meeting of the minds?

5. A buyer of house before buying was allowed to investigate for himself the said house, even after the seller had told him about it. The seller did nothing to prevent the investigation from being completed. Later the buyer brought an action to annul the contract, alleging that false representations had been made to him. Will the action prosper?

6. X and Y entered into a contract with Z. X's consent was obtained only because Y had deceived or defrauded him. May X ask for annulment of the contract with X?

7. Because it's boring, A and B executed a deed of sale although they did not intent to be bound at all by the contract. Is the contract valid?

8. If a particular car is sold for $100,000, what is the object and what is the case?

9. The guardian of Anne sold Anne's mansion worth $1 million for $500,000. May the contract be rescinded on the ground of lesion?

10. Alucard sold his house worth $100,000 to Balmond for only $50,000 because Alucard did not know the true value of the house. May the contract of sale be rescinded?