1L of a gas is at a pressure of `10^(-6)` mm of Hg at `25^(@)C`. How many molecules are present in the vessel.

Options

A. `3.2xx10^(6)`
B. `3.2xx10^(13)`
C. `3.2xx10^(10)`
D. `3xx10^(4)`

Answer

B

Explanation

`(P_(1)V_(1))/(T_(1))=(P_(2)V_(2))/(T_(2)) therefore (10^(-1)xx1000)/(298)=(760xxV_(2))/(273)`
or `V_(2)=1.2xx10^(-6)"cc (at STP)"`
No. of molecules `=(6.02xx10^(23))/(22400)xx1.2xx10^(-6)`
`=3.2xx10^(13)`