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Effusion Times and Atomic Masses

APCHEM-TJNR8K

Helium gas (atomic mass 4.0 amu) takes 10 seconds to effuse through a particular orifice at a certain combination of temperature and pressure. An unknown gas, X, takes 30 seconds to effuse through the same orifice and under the same conditions.

Which of the following is the particle mass of Gas X?

A

0.44 amu

B

6.9 amu

C

12 amu

D

36 amu