Explanation: just add the atomic masses on the periodic table together for each atom.
<span> A homogeneous mixture is composed of a single visible phase while a heterogeneous mixture has two or more</span>
pV = nRT
p = nRT/V
p= 1 x 0.08205 x 1000/ 2
p = 41.025 Pa
Edit: The unit should be atm instead of Pa, as pointed out by a nice human being.