From what I can tell, the most prominent characteristic of life is its changeability and unpredictability. These factors affect just about everyone's life, no matter when or where they live or lived.
no
Decay
it must have a ph of 7
it must have a ph of 7
It depends what on what balance your talking about
Carbon dioxide is NOT a life characteristic.
Trait i believe. Since its more of a hereditary thing it would not be considered a characteristic which are aspects of someones character, formed by their life experiences.
Adaptation
One single characteristic, if you have to pick one, is that it multiplies, or reproduces.
You would be talented and articulate. Affectionate, yet shy, you would seek peace somewhere throughout your life.
Primarily so that there can be more Life.
React to stimulus