I have never heard anyone ever say anything about aliens only living by using the same metabolistic processes as humans... But.. there may likely be another planet out there that does use oxygen, although at a different percentage from Earths. Anyways, even if we do find "other" life forms, who's to say that they're on the same level as us? Have you ever considered the fact that ants to us are like we are to other life forms out there and maybe they don't want or can't communicate with us because they see themselves as superior?
Hope that helps!
The sun's rays hit the Earth at a extreme angle, which causes the days to become shorter, so yes, the sun's rays do hit the Earth at a extreme angle.
When two atoms are bonded together, the atom that is LEAST likely to attract electrons to itself is
the atom with the smallest electronegativity
Answer:
The half life is 
Explanation:
The half life of a first order reaction is mathematically represented as
Substituting 
for the rate constant
