Advertisements
Advertisements
प्रश्न
Which of the following is present today but was absent about 3.5 billion years ago?
विकल्प
nitrogen
oxygen
hydrogen
methane
MCQ
Advertisements
उत्तर
Oxygen
Explanation:
Free oxygen was absent from the reducing primitive atmosphere and accumulated later after photosynthetic organisms evolved. Nitrogen, hydrogen and methane were among gases associated with early Earth.
shaalaa.com
क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
