True or False and why

00 An agreement to attend a birthday party is an obligation Expense incurred for transportation and lawyers fees in enforcing an obligation are collectible from the debtor by way of exemplary damages Negotiorum gestio is based on the principle that no one should unjustly enrich self at the expense of another There is no contract in solutio indebiti but an obligation is created An obligor is the one who committed oneself to pay or perform an obligation in favor a of another Liability arising from negligence arises when there is a contract between parties but it was recklessly performed A person acting within one's rights cannot be liable for anything A contract is not valid until it is written