I put Penicillin first because of how important medicine like this can be and how it revolutionized the medicine we have today. I put the phone second because they could save you life. I put the car third because it is ready for emergencies. I put the radio fourth because it can spread helpful information and put you in a better mood. I put the plane last because it is not necessary for most people, but it can come in handy for transporting people and different goods.