A gas at 300 K has pressure `4 xx 10^(-10) N//m^(2)`. IF `k = 1.38 xx 10^(-23) J//K`, the number of `"molecule"// cm^(3)` is of the order of

Options

A. `10^(3)`
B. `10^(5)`
C. `10^(6)`
D. `10^(9)`

Answer

B

Explanation

using, `PV=nRT =nN((R)/(N))T=nNt_(B)T`
`(nN)/(V)=(P)/(k_(B)T)=` number of molecules per `m^(3)`
`therefore` Number of molecules `//cm^(3)=(P)/(k_(B)T)xx10^(-6)`
`=(4xx10^(-10)xx10^(-6))/(1.38xx10^(-23)xx300)=10^(5)`