Calcium nitride contains 81.1% by mass of the metal. Calculate the empirical formula of calcium nitride. Show your working.

                                                     Ca             NPercentage:                         81.1%       18.9%Relative atomic mass:     40.1             14Ratio:                                 (81.1/40.1)   (18.9/14)                                                2.02      :       1.35                                                  1.5:1                                                  3:2Empirical formula: Ca₃N₂