At T(k), copper (atomic mass=635 u) has fcc unit cell structure with edge length of `x A`. What is the approximate density of Cu in `g cm^-3` at that temperature? (`N_A=6.0 times 10^23 mol^-1`)

Options

A. `42.3/x^3`
B. `423/x^3`
C. `423/x^3`
D. `212/x^3`

Explanation

Given,
fcc unit cell is present, Z=4
Edge length = `x A`
Atomic weight =`63.5 g mol^-1`
`becauseDensity , d=(Z times at omic weight )/(a^3 times N_A)`
where, a= edge length
` d=(Z times at omic weight )/(x^3times6.023 times10^23 times(10^-8)^3)`
`=(4 times63.5)/(x^3 times6.023 times10^23 times10^-24)`
`d=423.0/x^3`
Hence, option (c ) is correct.