A metal crystallises into two cubic phases , face-centered cubic (fcc) and body centered (bcc) whose unit lengths are $3.5 \;and\;3.0 A^{\large\circ}$ respectively . Calculate the ratio of densities of fcc and bcc.

Question

$(a)\;2.1\qquad(b)\;3.3\qquad(c)\;1.259\qquad(d)\;2.259$