An element forms crystals of density of `8570kgm^(-3)`. The packing efficiency is 0.68. If the closest distance between neighbouring atoms is 2.86 Å. The mass of one atom is (1 amu = `1.66xx10^(-27)` kg)

Options

A. 186 amu
B. 93 amu
C. 46.5 amu
D. 43 amu

Answer

B

Explanation

For bcc z = 2 (Packing efficiency = 0.68)
`sqrt3a=2(r_(A)-r_(A))rArrsqrt3a==2xx2.86rArra=3.3`
`d=(2xxM)/(a^(3)N_(A))`
`8570xx10^(3)=(2xxM)/((3.3xx10^(-10)m)^(3)xx6.02xx10^(23))=93g"mol"^(-1)=93u`