We have that the Density of metal X is mathematically given as
[tex]\phi= 6359.44 Kg/m^3[/tex]
Generally the equation for the side of fcc is mathematically given as
[tex]Fcc=2*\sqrt(2) *radius of metal\\\\Fcc== 2*1.414*125\\\\Fcc 353.5*10^-12 m \\\\[/tex]
Where
volume of 1 unit cell of fcc
[tex]FccV= (353.5*10^-12)^3\\\\FccV =44174155.375 *10^-36 m^3\\\\[/tex]
And
weight of 1 atom
[tex]Wa= moleular weight / avogadro number\\\\Wa = 42.3/(6.023 *10^23) \\\\Wa= 7.023 *10^-23 gm/atom\\\\[/tex]
Therefore
density
[tex]\phi= (28.0923 *10^-26) / ( 44174155.375 *10^-36)[/tex]
[tex]\phi= 6359.44 Kg/m^3[/tex]
For more information on Atoms visit
https://brainly.com/question/13981855