A closed vessel contains an equal number of molecules of `N_2` and `O_2` at a total pressure of 650 mm of Hg. If `N_2` is completely removed the pressure will,

Options

A. drop to 650/3
B. drop to 650/2
C. remain unchanged
D. become 650 x 2.

Answer

B

Explanation

Equal number of molecules means equal number of moles i.e., equal mole fraction since partial pressure a mole fraction.
`therefore p_(N_(2)) = p_(O_(2))` or `p_(O_(2)) = 650/2` mm of Hg.