At STP, a container has 1 mole of Ar, 2 mole of `CO_(2)`, 3 moles of `O_(2)` and 4 moles of `N_(2)`. Without changing the total pressure if one mole of `O_(2)` is removed, the partial pressure of `O_(2)`

Options

A. is changed by about 26%
B. is halved
C. is unchanged
D. changed by 33%

Answer

A

Explanation

In first case : `n_(Ar) = 1, n_(CO_(2)) = 2, n_(O_(2)) = 3`
`n_(N_(2)) = 4`
`n_(Ar) + n_(CO_(2)) + n_(O_(2)) + n_(N_(2)) = 10`
`n_(O_(2)) = 3//10`
`:. P_(O_(2)) = 3P//10`
(where P is the total pressure).
In seconds case : `n_(O_(2)) = 2//9 , P'_(O_(2)) = 2P//9`
Decrease in partial pressure of
`O_(2) = (3P)/(10) - (2P)/(9) = (7P)/(90)`
% Decrease in partial pressure of `O_(2)`
`= (7P//90)/(3P//10) xx 100 = (700)/(27) = 26%`