Which of the following was likely to have been absent in a free molecules state , in the primitive atmosphere of the earth ?

Which of the following was most likely to have been absent in free form in the primordial atmosphere at the time of origin of life Or Miller performed experiment to prove molecular evolution of life. Which molecule was not present in Miller's experiment

According to Oparin , the primitive atmosphere of the Earth is ?

According to Oparin , the primitive atmosphere of the Earth is ?

The atmosphere of primitive earth was

The atmosphere of primitive earth was

Was oxygen present in free state in primitive earth's atmosphere?

Which of the following molecules have shape like CO_(2) -

Which gas was absent in the atmosphere of primitive earth ?

Which gas was absent in the atmosphere of primitive earth?