* The Atmosphere: About 21% of the Earth's atmosphere is composed of oxygen gas (O2). This is the oxygen we breathe.
* Water (H2O): Water molecules contain oxygen atoms. This means that oceans, lakes, rivers, and even the water in your body contain oxygen.
* The Earth's Crust: Oxygen is the most abundant element in the Earth's crust, making up about 46.6% of its mass. It is found in various minerals and rocks.
* Living Organisms: Oxygen is essential for most living organisms, including plants and animals. Plants produce oxygen during photosynthesis, and animals use it for respiration.
So, oxygen is all around us, even if we don't always see it!
