Brain › Science & NatureWhich gas forms about 78% of the Earth’s atmosphere?NitrogenOxygenArgonCarbon DioxideAnswerThe correct answer is A) Nitrogen.More Science & Nature questionsWhich of these bones is hardest to break?What does LASER stand for?The asteroid belt is located between which two planets?What is the chemical makeup of water?What is the powerhouse of the cell?What did Gregory Mendel use to test genetic crossovers?Play Brain · Practice