# 2g of gas A introduced in a evacuated flask at flask at 25 degree celcius. The pressure of the gas is 1atm. now 3g of another gas B is introduced in the same flasks total pressure becomes 1.5atm. The ratio of molecular mass of A and B is?

3g of B = .5 atm => lets assume that this is **x **moles

2g of A = 1 atm => so this is **2x** moles

**2g/2x = m _{a}** (m = molecular mass) and

**3g/x = m**

_{b}m_{a}/m_{b} = 2g/2x * x/3g = 2/2 * 1/3 = **1/3 **