Science
100
The process by which plants, algae, and some bacteria convert light energy from the sun into chemical energy / food
What is PHOTOSYNTHESIS 
200
The FOURTH planet from the Sun
What is MARS
300
The three states of matter
What is SOLID, LIQUID, GAS 
400
The hardest natural material on the planet
What is DIAMOND 
500
The percentage of the Earth that is covered by land
What is 29%