Question

The term, reducing atmosphere for the early earth means that the atmosphere

• A. Was much thinner around the surface of the earth than now
• B. Contained only two or three kinds of gases
• C. Contained little or no free oxygen
• D. Contained little or no free nitrogen

Answer 1

The correct option is C Contained little or no free oxygen

Scientists believe that the Earth was formed about 4.5 billion years ago. Its early atmosphere was probably formed from the gases given out by volcanoes. It is believed that there was intense volcanic activity for the first billion years of the Earth's existence. The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. There were smaller proportions of water vapour, ammonia and methane.

So the correct option is 'contained little or no free oxygen'.