1. What is the most common heat transfer mechanism in solids?
Conduction - the particles are close together

2. What is the most common heat transfer mechanism in liquids and gases?
Convection - the particles are fluid

3. What is the only heat transfer mechanism in a vacuum?
Radiation - both conduction and convection require particles

4. Why can't conduction happen in a vacuum?
Conduction requires particles

5. What happens to the space between the molecules in a gas when you heat it?
The space between the molecules increases when you heat it

6. What happens to the density of a gas when you heat it?
The density of a gas increases when you heat it

7. Why can't convection happen in a solid?
Because the particles in a solid aren't fluid