The correct option is B 5.0kg/m3
AB has rock-salt (A:B::1:1) structure, i.e., fcc structure (n=4) and formula mass of AB is 6.023 y g having closest distance A−By1/3 nm. Therefore, edge length of unit cell
(a)=2(A++B−)=2×y1/3×10−9m
∴ DensityofAB=n×formulamassAv.no.×V=n×formulamass6.023×1023×a3
=4×6.023×y×10−36.023×1023×(2y1/3×10−9)3 (formula mass in kg)
=5.0kg/m3