An element crystallises in fee lattice having edge length `350` Maximum raduis of the atoms which can be placed in the internal site without distoring the structure is

Options

A. `58.55` pm
B. 117 pm
C. `51.23` pm
D. 83 pm

Answer

c

Explanation

For fcc stracture
`((r_(+))/(r_(-))) = 0.414` for octahedral void
`= 0.225` for tetrabeederal void
Thus maximum packing can be octabodral void
`r_(+) = 0.414 r`
Also `r_(-) = (a)/(2sqrt(2)`
`:. r_(+) = 0.414 (a)/(2sqrt(2)) = 0.414xx(350)/(2sqrt(2)) = (144.9)/(2sqrt(2)) = 51.23` pm