Unsaturation (IHD) 2 hydrogen Needed
IHD = [(2n+2) -H]/2
(H: X=1, N=-1, O= zero)
Unsaturation:
Double bonds = 1
Rings = 1
Triple Bonds = 2
The degrees of unsaturation in a molecule are additive — a
molecule with one double bond has one degree of unsaturation, a molecule with
two double bonds has two degrees of unsaturation, and so forth.
Light basically evaporates pigments such as colored paper. Exposed pigment fading is kind of like getting colored paper wet. It will fade and bleed.
Answer:
Nitrogen, 
Explanation:
Hello,
This is a clear example of what the ideal gas equation is used for, thus, from its mathematical definition:

One can spell it out in terms of mass and molar mass:

Now, solving for the molecular mass,
:

Now, by taking into account that the gas is diatomic, the matching gas turns out to be nitrogen.
Best regards.