Given mass of aluminium , mAl =48 g
Mass of tungsten , mW = 56 g
Total mass , M = mAl + mW = 48+56 = 104
g
Number of moles of Al , nAl = mAl / atomic
mass of Al
                                      Â
= 48 g / 26.98 (g/mol)
                                      Â
= 1.78 mol
Number of moles of W , nW = mW / atomic
mass of W
                                      Â
= 56 g / 183.85 (g/mol)
                                      Â
= 0.304 mol
Total number of moles , N = nAl + nW =
1.78+0.304 = 2.084
So atomic percent of tungsten = (nW / N )x100
                                          Â
= (0.304/2.084)x100
                                          Â
= 14.6 %