How many oceans are there on Earth?
5 (Arctic, Atlantic, Indian, Pacific, and Southern)
Which gas is essential for life on Earth?
1. Oxygen (O2), medical use, 2. Nitrogen (N2): fire suppression, provides an inert atmosphere 3. Helium (He): balloons, medical equipment 4. Argon (Ar): welding
How many continents are there on Earth ?
7 (Asia, Africa, North America, South America, Europe, Australia and Antarctica)
Which planet has conditions similar to those on Earth?
Mars
How many moons orbit Earth?
1