Calculate the number of vacancies per cubic meter in unknown materials at $850C.$ The energy for vacancy formation is $1\mathrm{.}08e\frac{V}{a}$tom. Furthermore, the density and atomic weight for tis material are $6\frac{g}{c}{m}^3$ and $40\frac{g}{m}ol,$ respectively.

Select one:

a$.$

$1\mathrm{.}29{10}^{24}{m}^{-3}$

b$.$

$1\mathrm{.}5{10}^{24}{m}^{-3}$

c$.$

$1\mathrm{.}8{10}^{24}{m}^{-3}$

d$.$

$0\mathrm{.}062{10}^{24}{m}^{-3}$