2 dm3 of a gas weighs 4.12 g at S T.P. Calculate the molecular weight of the gas.

We know that g. mol. wt. of a gas occupies volume at                STP = 22.4 dm3.2 dm3 of the gas weighs =4.12g22.4 dm3 of the gas wieighs =4.12g2dm3×22.4dm3=46.1g∴   Mol wt. of gas =46.1gmol−Ans.