1. (i) What is the volume (measured in dm3 or litres) occupied by one mole of a gas at STP?   2. (ii) 112 cm3 (at STP) of a gaseous fluoride of phosphorus has a mass of 0.63g. Calculate the relative molecular mass of the fluoride. If the molecule of the fluoride contains only one atom of phosphorus, then determine the formula of the phosphorus fluoride. (F = 19; P = 31)