Let the inter molecular distance be D
Then in a volume of 34πD3 there is only one molecule.
34πD3P=(NA1)RT
D=(4πNAP3RT)31
Substituting P=4×10−10Pa,R=8.3,NA=6×1023,T=300K
D=0.2mm
JEE Main 2014 — Physics Thermodynamics
Modern vacuum pumps can evacuate a vessel down to a pressure of 4.0×10−15 atm. at room temperature (300 K). Taking R = 8.3 JK−1 mole−1, 1 atm = 105 Pa and NAvogadro=6×1023mole−1, the mean distance between molecules of gas in an evacuated vessel will be of the order of :
Held on 9 Apr 2014 · Verified 6 Jul 2026.
0.2μm
0.2mm
0.2cm
0.2nm
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