Answer:
Mass percentage of gold : 33.35%
Mass percentage of silver: 62.80%
Mass percentage of copper : 3.85%
Explanation:
![N=n\times N_A](https://tex.z-dn.net/?f=N%3Dn%5Ctimes%20N_A)
Where : N = Number of atoms
n = moles
= Avogadro number
Let the total atoms present in the alloy be 100.
Atom percentage of silver = 44.9%
Atoms of of silver = 44.9% of 100 atoms = 44.9
Atomic weight of silver = 107.87 g/mol
Mass of 44.9 silver atoms = 107.87 g/mol × 44.9 = 4,843.363 g/mol
Atom percentage of gold= 46.3%
Atoms of of gold = 46.3% of 100 atoms = 46.3
Atomic weight of gold = 196.97 g/mol
Mass of 44.9 gold atoms = 196.97 g/mol × 46.3 = 9,119.711 g/mol
Atom percentage of copper = 8.8 %
Atoms of of copper = 8.8% of 100 atoms = 8.8
Atomic weight of copper = 63.55 g/mol
Mass of 44.9 copper atoms = 63.55 g/mol × 8.8 = 559.24 g/mol
Total mass of an alloy :4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol
Mass percentage of gold :
![\frac{4,843.363 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=33.35 \%](https://tex.z-dn.net/?f=%5Cfrac%7B4%2C843.363%20g%2Fmol%7D%7B4%2C843.363%20g%2Fmol%20%2B%209%2C119.711%20g%2Fmol%20%2B%20%20559.24%20g%2Fmol%7D%5Ctimes%20100%3D33.35%20%5C%25)
Mass percentage of silver:
![\frac{9,119.711 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=62.80\%](https://tex.z-dn.net/?f=%5Cfrac%7B9%2C119.711%20g%2Fmol%7D%7B4%2C843.363%20g%2Fmol%20%2B%209%2C119.711%20g%2Fmol%20%2B%20%20559.24%20g%2Fmol%7D%5Ctimes%20100%3D62.80%5C%25)
Mass percentage of copper :
![\frac{559.24 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=3.85\%](https://tex.z-dn.net/?f=%5Cfrac%7B559.24%20g%2Fmol%7D%7B4%2C843.363%20g%2Fmol%20%2B%209%2C119.711%20g%2Fmol%20%2B%20%20559.24%20g%2Fmol%7D%5Ctimes%20100%3D3.85%5C%25)