1. Oxygen is a colorless, odorless and tasteless gas at normal temperature and pressure, and turns blue after liquefaction.

2. The molecular weight of oxygen is 32.0, the melting point (101.325Kpa) is -218.8℃, the boiling point (101.325kpa) is -183.0℃, the liquid density (90.18k, 101.325kpa) is 1141kg/m³, and the gas density (0℃, 101.325kpa) ) Is 1.4289kg/m³, the critical temperature is -118.6℃, and the critical pressure is 5043kpa.

3. Oxygen itself does not burn, but it can support combustion. Oxygen is chemically active and can combine with various elements to emit light and heat and burn immediately.

4. Oxygen is slightly soluble in water, alcohol, etc.

5. The normal human system requires a certain concentration of oxygen, but too high or too low oxygen concentration will be harmful to people. Excessive oxygen partial pressure can cause "oxygen poisoning". Too low oxygen concentration will produce "hypoxia".