Solution:
Use the formula PV = nRT
P = 2 atm
V = 350 ml. = 0.35 L
R = 0.0821 L atm K-1 mol-1
T = 0º C = 273 K
Putting the values in given formula we get :
n = PV/RT
= 2 atm x 0.35 L/ 0.0821 L atm K-1 mol-1 x 273 K
= 0.0312 mol
Now weight of 0.0312 mol of gas is 1 gram
therefore weight of 1 mol of gas would be 1/0.0312 = 32 g mol-1
Since the gas is diatomic therefore weight of 1 mole atom = 16 g mol-1
Weight of 1 atom of gas = 16 g mol-1/ 6.022 x 1023 atom mol-1
= 2.65 x 10-23 g /atom