A compound formed by the element A and B crystallizes in the cubic structure, where A is at the corners of the cube and B is at body centre. What is the formula of the compound? If edge length is `5Å`, calculate the density of the solid. (Atomic weights of A and B are 60 and 90 respectively).

Explanation

Formula: `d=(Z xx M)/(a^(3) xx N_(A))`
Data: Edge length =(a) `=5 xx 10^(-8)` cm `N_(A) = 6.022 xx 10^(23)`
Molecular formula `=1/8 xx 8` (at corners) + 1(at centre)
= 1A + 1B
Molecular formula =AB Molecular mass = AB = 60 + 90 = 150.
Cubic unit cell is BCC = (Z)=2
`d=(2 xx 150)/((5 xx 10^(-8))^(2) xx 6.022 xx 10^(23))`
`d=3.98 g cm^(-3)`