[LHM]

1. Uranium hexafluoride is a gas used to affect the separation of the ²³⁵U isotope from ²³⁸U. The relative rate of effusion, that is the ratio of the rate of effusion of the ²³⁵U compound to the rate of the ²³⁸ compound, isU
A) 0.9940
B) 1.004
C) 1.006
D) 1.008

Isn't it just the square root of (238/235)=1.006, which is C? But why does the answer say it's B?

2. Which statement pertains to the measured pressure of gas collected when O₂ is collected over water?
A) It is greater than the pressure of dry O₂
B) It is less than the pressure of dry O₂
C) It is equal to the pressure of dry O₂
D) It varies inversely with the pressure of dry O₂

I thought that it would be B because the pressure of the water vapor would have to be subtracted from the pressure of the atmosphere, which would make the pressure of wet O₂ less than the pressure of dry O₂, so I picked B. Why is the answer A then?

Thanks

[Borek]

Isn't it just the square root of (238/235)=1.006, which is C? But why does the answer say it's B?

It is not U that is gaseous.

2. Which statement pertains to the measured pressure of gas collected when O₂ is collected over water?

You are asked about total gas pressure, not O₂ pressure.