CsCl crystallises in body centred cubic lattice. If 'a' is its edge length then which of the following expression is correct ?

Options

A. `r_(Ca^(+)) + r_(Cr^(-)) = 3a`
B. `r_(Ca^(+)) + r_(Cr^(-)) = (3a)/(2)`
C. `r_(Ca^(+)) + r_(Cr^(-)) = (sqrt(3))/(2)a`
D. `r_(Ca^(+)) + r_(Cr^(-)) = sqrt(3a)`

Explanation

`2 (r_(cg) oplus + r_(Cl) oplus ) = sqrt(3)a`
B = `(1)/(2) xx 6 = 3`
(face centre ) `therefore " " AB_(3)`