Question

The molecules in a perfect gas has mean kinetic energy (at 27°C) of 7 x 10^-4 erg and acceleration due to gravity 980 cm s⁻². Then, the number of molecules in 2 cc of this gas at 27° C at a pressure of 10 cm of Hg is

(a) 4.28 x 10⁷

(b) 3.52 x 10⁸

(c) 4.75 x 10⁸

(d) 5.71 x 10⁸

Answer 1

Answer is : (d) 5.71 x 10⁸

KE of the given gas at 27° C

∴ Number of molecules in the given volume = KE of given gas/KE of a molecule of gas