What is M ? please answer this question and box the answer. Thank you,

An isothermal ( T=0 Celsius) gas tank has a height of 142m. The gas pressure at the bottom of the tank is 4.75 bar, and at the top of the tank, the pressure is measured to be 4.51 bar. What is the molecular weight of the gas in this tank, in g/mol? ln(4.754.51)=8.311273.15m9.81(11+2)