Consider the following experiment: 
A Kr gas was allowed effuse through a small hole under constant pressure. The 2 L sample of Kr took 96.0 s to effuse. Another gas of unknown identity went through the same conditions. It took a 2 L sample of the unknown gas 55.5 s to effuse. Calculate the molar mass of the unknown gas. 

• A. 19.8 g/mol
• B. 20.2 g/mol
• C. 32.0 g/mol
• D. 28.0 g/mol