Are You Smarter Than a 5th Grader? The Ultimate Test Which planet is known as the "Red Planet"? Venus Mars Jupiter Saturn None What is the largest organ in the human body? Heart Brain Liver Skin None Which two gasses make up the majority of Earth's atmosphere? Oxygen and nitrogen Oxygen and carbon dioxide Nitrogen and carbon dioxide Nitrogen and helium None What is the largest ocean on Earth? Indian Ocean Atlantic Ocean Pacific Ocean Arctic Ocean None Which of the following is a primary source of energy for the human body? Protein Carbohydrates Vitamins Fats None Time's up Most Popular Most Popular
