I think these two variables are sufficient to completely specify the state.
In an isolated room with air only ,the volume is fixed.Mass ,density and its specific volume can be easily known.
Other thermodynamic properties like entropy, enthalpy etc are also fixed at a given temperature & pressure.
Answer:
Angle of first order maximum, 
Explanation:
Given that,
Wavelength of the light, 
Number of lines, N = 8000 per cm
The relation between the number of lines and the slit width is given by :


The equation of grating is given by :

n = 1



So, the angle of the first-order maximum is 21.19 degrees. Hence, this is the required solution.
Answer:
r1 -r2 = 3.75cm
Explanation:
Check the attached file for the solution