Answer:
number of molecules= 2.83 x 10^19
Step-by-step explanation:
0.04 % means 0.04 L CO_2 in 100 L atmosphere
so for 2.9 L atmosphere CO2 vol = ( 0.04/100) x 2.9 = 0.00116
T = 27°C = 300 K , P = 1 atm ,
n = PV/RT = ( 1 x 0.00116) ÷ ( 0.08206x300) = 4.71×10^{-5}
number of molecules = 6.023 x 10^23 x 4.71×10^{-5} = 2.83 x 10^19