The number of unit cells in 8 gm of an element X( atomic mass 40 ) which crystallizes in bcc pattern in `( N_(A) ` is the Avogadro number)

Options

A. `6.023xx 10^(23)`
B. `6.023 xx 10^(22)`
C. `60.23 xx 10^(23)`
D. `((6.023 xx 10^(23))/(8xx 40))`

Explanation

In bcc unit cell 2 atom = 1 unit cell
1 mole contains 6.023 `xx 10^(23)` atoms
`0.2 ` mole contains 0.2 `xx 6 .023 xx 10^(23) ` atoms
`((1 unit cell)/( 2 atom)) xx 0.2 xx 6.023 xx 10^(23) = 6.023 xx 10^(22)` unit calls