`1000 ml` of a gas A at `600 "torr"` and `500 ml` of a gas B at `800 "torr"` are placed in a `2L` flask. The final pressure will be

Options

A. `2000 "torr"`
B. `1000 "torr"`
C. `500 "torr"`
D. `1400 "torr"`

Answer

C

Explanation

From Dalton's partial pressure law
`P_(1)=(1000)/(1500)xx600+(500)/(1500)xx800`
`=400+(800)/(3)=(2000)/(3)"torr"`.
`V_(1)= 1500mL`
`P_(2)=? V_(2)= 2L= 2000mL`
From `P prop (1)/(V)`
`(P_(1))/(P_(2))=(V_(2))/(V_(1))= implies (2000//3)/(P_(2))= (2000)/(1500)`
`implies P_(2)= (1500)/(3)= 500 "torr"`