Question
Question: Which one is present today but was absent about 3 to 5 million years ago?...
Which one is present today but was absent about 3 to 5 million years ago?
A
N2
B
O2
C
H2
D
CH2
Answer
O2
Which one is present today but was absent about 3 to 5 million years ago?
N2
O2
H2
CH2
O2