Why the atmosphere on Venus has almost never form oxygen?

Question

PLanet Venus has an atmosphere which is over 90% CO2, and the surface temperature is 477 degre celcius.

Answer 1

Oxygen is a very reactive gas that combines with almost anything, and consequently cannot exist in a free state without something to produce it. That "something" on Earth is life (green plants), which give off oxygen as a byproduct of photosynthesis. If all plant life were to die off, the oxygen in our atmosphere would rapidly combine chemically with other substances.

Answer 2

Atmosphere

Main article: Atmosphere of Venus

Venus has an extremely thick atmosphere, which consists mainly of carbon dioxide and a small amount of nitrogen. The pressure at the planet's surface is about 90 times that at Earth's surface—a pressure equivalent to that at a depth of 1 kilometer under Earth's oceans. The enormously CO2-rich atmosphere generates a strong greenhouse effect that raises the surface temperature to over 400 °C. This makes Venus' surface hotter than Mercury's, even though Venus is nearly twice as distant from the Sun and receives only 25% of the solar irradiance.
Cloud structure in Venus' atmosphere, revealed by ultraviolet observations
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Cloud structure in Venus' atmosphere, revealed by ultraviolet observations

Studies have suggested that several billion years ago Venus' atmosphere was much more like Earth's than it is now, and that there were probably substantial quantities of liquid water on the surface, but a runaway greenhouse effect was caused by the evaporation of that original water, which generated a critical level of greenhouse gases in its atmosphere.[9] Venus is thus an example of an extreme case of climate change, making it a useful tool in climate change studies.

Thermal inertia and the transfer of heat by winds in the lower atmosphere mean that the temperature of Venus' surface does not vary significantly between the night and day sides, despite the planet's extremely slow rotation. Winds at the surface are slow, moving at a few kilometers per hour, but because of the high density of the atmosphere at Venus' surface, they exert a significant amount of force against obstructions, and transport dust and small stones across the surface.[10]

Above the dense CO2 layer are thick clouds consisting mainly of sulfur dioxide and sulfuric acid droplets.[11] These clouds reflect about 60% of the sunlight that falls on them back into space, and prevent the direct observation of Venus' surface in visible light. The permanent cloud cover means that although Venus is closer than Earth to the Sun, the Venusian surface is not as well heated or lit. In the absence of the greenhouse effect caused by the carbon dioxide in the atmosphere, the temperature at the surface of Venus would be quite similar to that on Earth. Strong 300 km/h winds at the cloud tops circle the planet about every four to five earth days.[12]

Answer 3

no life on venus (apparently)