A candle is burnt in a beaker until extinguishers itseft. A sample of gaseous mixutre in the beaker contains `6.08 xx 10^(20)` molecules of `O_(2)`, and `0.50 xx 10^(20)` molecules of `CO_(2)`. The total pressure is `734 mm` of `Hg`. The partial pressure of `O_(2)` would be

Options

A. `760.0 mm "of" Hg`
B. `76.0 mm "of" Hg`
C. `7.6 mm "of" Hg`
D. `0.76 mm "of" Hg`

Answer

B

Explanation

`p_(O_(2)) = P_("Total") xx chi_(O_(2))` (moles fraction of `O_(2))`
`chi_(O_(2)) = (n_(O_(2)))/(n_(O_(2)) + n_(N_(2)) + n_(CO_(2)))`
`chi_(O_(2)) = (0.76 xx 10^(20))/((0.76 + 0.50 + 6.08) xx 10^(10)) = (0.76)/(7.34)`
`p_(O_(2)) = P_("Total") xx chi_(O_(2)) = 734 xx (0.76)/(7.34)`
`= 76.0 mm "of" Hg`.