Gas Effusion Rate Problem: He, Cl2, H2, Kr, Rn

[Navygal]

The Problem
A sample of N2 gas is contaminated with a gas. It is found that that contaminant effuses at 0.25 times the rate of N2. What is the contaminating gas?

Choices are: He, Cl2, H2, Kr, Rn

Homework Equations

Rate x/Rate N2 = (square root of:) Mass N2/Mass x

Where Rate x =0.25 Rate N2

The Attempt at a Solution

By plugging in the values I get a mass of x that is over 400, and none of the above choices weight that much

Another option I tried is using just Nitrogen instead of N2 which gives me Mass x = 224 which comes close to the 222 that I got. But I have a feeling that it's wrong and not sure how to justify my answer
Any help would be greatly appreciated

 

[Char. Limit]

Could you show what you did? I didn't get either of your answers.

 

[chemisttree]

The Problem
A sample of N2 gas is contaminated with a gas. It is found that that contaminant effuses at 0.25 times the rate of N2. What is the contaminating gas?

Choices are: He, Cl2, H2, Kr, Rn

Homework Equations

Rate x/Rate N2 = (square root of:) Mass N2/Mass x

Where Rate x =0.25 Rate N2

The Attempt at a Solution

By plugging in the values I get a mass of x that is over 400, and none of the above choices weight that much

Another option I tried is using just Nitrogen instead of N2 which gives me Mass x = 224 which comes close to the 222 that I got. But I have a feeling that it's wrong and not sure how to justify my answer
Any help would be greatly appreciated

If you show us your actual math I'm sure the mistake will present itself. You have the right idea but the arithmetic is off.