Venus is so hot because it is surrounded by a very thick atmosphere which is about 100 times more massive than our atmosphere here on Earth. As sunlight passes through the atmosphere, it heats up the surface of Venus. ... The heat becomes trapped and builds up to extremely high temperatures.
Air is a mixture.
as per definition, mixture is a combination we get after adding two or more things together in any proportion.
air is a mixture because it contains a number of gases like nitrogen , oxygen, carbon dioxide. it also contains dust particles, small organisms, water vapors etc.
carbon monoxide is not a mixture as it is formed from fixed proportion of carbon and oxygen.
similarly, water is is not a mixture as it is formed from fixed proportion of hydrogen and oxygen.
