A compound contains two elements X and Y percentage of X is 20% (At.wt = 40)and that of Y is 80% (At.wt =80). The empirical formula of the compound is

Explanation

To determine the empirical formula of the compound, we need to calculate the number of moles of each element in the compound.Let's assume that we have 100 grams of the compound. Then, the mass of element X is 20 grams and the mass of element Y is 80 grams.The number of moles of element X is calculated as follows:Number of moles of X=Mass of X Atomic weigth of X =40/20 =0.5The number of moles of element Y is calculated as follows:Number of moles of Y=Mass of Y Atomic weigth of Y =80/80 =1The empirical formula of the compound is then determined by dividing the number of moles of each element by the smallest number of moles. In this case, the smallest number of moles is 0.5, so we divide both numbers of moles by 0.5:Empirical formula=X1 Y2 Therefore, the answer to your question is a. XY2.