Question

The primitive atmosphere was reducing since ______

(a) Hydrogen atoms are very few

(b) Hydrogen atoms were active and many in number

(c) Helium atoms were more

(d) Oxygen atoms were more

This question was posed to me at a job interview.

Question is taken from Evolution in division Evolution of Biology – Class 12

Answer 1

The correct option is (b) Hydrogen atoms were active and many in number

To explain I would say: The active hydrogen atoms reacted with free oxygen atoms forming water. So, the primitive atmosphere was reducing without free oxygen unlike the present oxidizing atmosphere with free oxygen.