A metal crystallizes in `bcc` lattice. The percent fraction of edge length not covered by atom is

Options

A. `10.4%`
B. `13.4%`
C. `12.4%`
D. `11.4%`

Answer

B

Explanation

For bcc, `r = (sqrt(3))/(4)a `
Edge length not covered by atom `= a - 2r`
`= a-2xx (sqrt(3))//(4)a`
`= a[(2-sqrt(3))/(2)]`
`:.%` of fraction not covered `= (a[(2-sqrt(3))/(2)])/(a) xx 100`
`= 0.314 xx 100 = 13.4%`