The density of `KBr` is `2.75 g cm^(-3)`. The length of the unit cell is `654` pm. Atomic mass of `K = 39, Br = 80`. Then what is true about the predicted nature of the solid?

Explanation

For KBr, M=39+80=119
`a=(654xx10^(-10))`cm
`d=2.75 "g/cm"^3`
`therefore rho=(ZxxM)/(N_0xxa^3)`
or, `Z=(rhoxxN_0xxa^3)/M`
`Z=(2.75xx6.02xx10^23xx(654xx10^(-10))^3)/119`
On solving Z=3.89=4
hence, it is a fcc lattice.