Consider the arrangement of bulbs shown in the drawing. Each of three bulbs contains a gas at pressure shown. What is pressure of system when all stopcocks are opened. Assuming that temperature remain constant. (Neglect the volume of capollary tubing connecting bulbs)

Options

A. 440 torr
B. 200 torr
C. 360 torr
D. 320 torr

Answer

A

Explanation

After all stopcocks are opened, gases move unit partial pressure becomes same in all bulbs
For `O_(2)` gas
`P_(1) V_(1) = P_(2) V_(2)`
`P_(1) = 300` torr, `P_(2)` ?
`V_(1) = 1` litre, `V_(2) = 2.5` litre
`300 xx 1 = P_(2) xx 2.5`
`P_(2) = 120` torr
For He gas
`P_(1) V_(1) = P_(2)V_(2)`
`P_(1) = 600` torr, `P_(2) =` ?
`V_(1) = 1` litre, `V_(2) = 2.5` litre
`600 xx 1 = P_(2) xx 2.5`
`P_(2) = 240` torr
For `N_(2)` gas
`P_(1)V_(1) = P_(2)V_(2)`
`P_(1) = 400` torr, `P_(2) =` ?
`V_(1) = 0.5` litre, `V_(2) = 2.5` litre
`400 xx (1)/(2) = P_(2) xx (5)/(2)`
`P_(2) = 80` torr
Pressure of system
`= P_(O_(2)) + P_(N_(2)) + P_(He)`
`= 120 + 80 + 240`
`= 440` torr