If `10^(-4) dm^(3)` of water is introduced into a `1.0 dm^(3)` flask to `300K` how many moles of water are in the vapour phase when equilibrium is established ? (Given vapour pressure of `H_(2)O` at `300K` is `3170Pa R =8.314 JK^(-1) mol^(-1))` .

Options

A. `4.46 xx 10^(-2) mol`
B. `1.27 xx 10^(-3) mol`
C. `5.56 xx 10^(-2) mol`
D. `1.53 xx 10^(-2) mol`

Answer

B

Explanation

`pV=nRT`
`n=(pV)/(RT)`
`p=3170Pa`
`R=8.314xx10^(3)"Pa dm"^(3)K^(-1)"mol"^(-1)`
`V="1 dm"^(3)" (volume of vapours is same as that of flaks)"`
`n=(3170xx1)/(8.314xx10^(3)xx300)`
`n=1.27xx10^(-3)" mol"`