1. OUT OF OXYGEN
TOPIC
PRESENT BY
GROUP 5

2. oxygen
Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table and is a highly reactive nonmetallic element and oxidizing agent that readily forms compounds (notably oxides) with most elements. Oxygen is the third-most abundant element in the universe, after hydrogen and helium. At STP, two atoms of the element bind to form oxygen, a diatomic gas that is colorless, odorless, and tasteless, with the formula O2.
Many major classes of organic molecules in living organisms, such as proteins, nucleic acids, carbohydrates, and fats, contain oxygen, as do the major inorganic compounds that are constituents of animal shells, teeth, and bone. Most of the mass of living organisms is oxygen as it is a part of water, the major constituent of lifeforms (for example, about two-thirds of human body mass). Elemental oxygen is produced by cyanobacteria, algae and plants, and is used in cellular respiration for all complex life. Oxygen is toxic to obligately anaerobic organisms, which were the dominant form of early life on Earth until O2 began to accumulate in the atmosphere. Free elemental O2 only began to accumulate in the atmosphere about 2.5 billion years ago during the Great Oxygenation Event, about a billion years after the first appearance of these organisms. Diatomic oxygen gas constitutes 20.8% of the volume of air. Oxygen is the most abundant element by mass in the Earth's crust as part of oxide compounds such as silicon dioxide, making up almost half of the crust's mass.

3. Concrete is a mixture of sand and gravel held together by a binding agent that is a mixture of calcium silicate hydrates and calcium hydroxide. The calcium hydroxide is the key ingredient in the CO2 mystery. Carbon dioxide diffusers into the porous structure of concrete then reacts with calcium hydroxide to from calcium carbonate and water
Ca(OH)2(s) + CO2(g) CaCO3(s) + H2O(l)

4. OXYGEN Oxygen is a colorless, odorless, tasteless gaseous chemical
element which appears in great abundance on Earth, trapped by the atmosphere. Many people are familiar with oxygen, because it is a vital component of the respiration process; without oxygen, most organisms will die within minutes.

5. Out of oxygen for human
Oxygen is important for human because everyone must use oxygen to breath for make heat and energy for the body this we call Metabolism.

6. HUMAN BRAIN However, our brain are important it also use oxygen but
if no oxygen our brain will be die . Therefore oxygen is very
important for human it make you feel fresh and happy We can’t stay in this world by no oxygen .If all of human don’t have oxygen to breath only few minute we will die.

7. OUT OF OXYGEN FOR ANIMALS
Animals also use oxygen to breath. If they don’t have oxygen they will be die. Same as human Therefore Oxygen is important for human and animal to live.

8. Oxygen in Water
Oxygen in water is known as dissolved oxygen or DO.  In nature, oxygen enters water when water runs over rocks and creates tremendous amounts of surface area.  The high surface area allows oxygen to transfer from the air into the water very quickly. 
When the water in a stream enters a pond, microorganisms in the pond begin to metabolize (break down) organic matter, consuming oxygen in the process.  This is another form of oxygen cycle - oxygen enters water in rapids and leaves water in pools. 
Oxygen uptake rate (O.U.R.) is the rate at which oxygen is consumed by living organisms in the water.  Since organisms are constantly using up oxygen in the water and oxygen is constantly reentering the water from the air, the amount of oxygen in water remains relatively constant.  In a healthy ecosystem, the rates of oxygen transfer (being used up) and oxygen uptake are balanced in the water. 

9. Out of oxygen for plant
Plant give out oxygen in the day time but in night time the plant take the oxygen in and give out carbon dioxide . However if no oxygen in the world the plant will can’t make the food. If in this world don have the plant we will don have the oxygen to breath.

10. Conclusion
Oxygen is very important for everything in the world. For example water (H2O), if no oxygen in the water. The water will be waste water. That mean the oxygen is very important for everything in the world.