Mass of liquid `= 148 - 50 = 98g`
Volume of liquid `= ("mass")/("density") = (98)/(0.98) = 100 mL`
Volume of vessel = Volume of liquid
Mass of gas `= 50.5 - 50 = 0.5 g`
On applying ideal gas equation, we have,
`PV = (w)/(m) RT`
`(760)/(760) xx (100)/(1000) = (0.5)/(m) xx 0.0821 xx 300`
`m = 123`