For offspring of to dominant appearing parents to appear recessive, both parents must be heterozygous, meaning they each have one dominant and one recessive allele. About 25% of their offspring will exhibit the recessive trait.
It will stay the same.
The mass isn't <em>going anywhere</em> (You did mention the jar was hypothetically and therefore hermetically sealed)
The only thing changing here is the density of the water in the jar (whether it be vapor, liquid or otherwise)
as the temperature drops and the vapour becomes liquid, the water will be more dense.
that's not saying that the weight won't increase as that is controlled by the force gravity exerts on the mass. (Hint: water is much more affected by gravity than air is)
Nitrogen is fixed or combined, in nature as nitric oxide by lightning and ultraviolet rays, but more significant amounts of nitrogen are fixed as ammonia, nitrites, and nitrates by soil microorganisms.
