AIPMT 2000
In cube of any crystal A-atom placed at every corners and B-atom placed at every centre of face. The formula of compound is
Explanation
A atoms are at 8 corners of the cube
$$ \therefore $$ No. of A atoms per unit cell = 8 $$ \times $$ $${1 \over 8}$$ = 1
B atoms are at the face centre of six faces.
$$ \therefore $$ No. of B atoms per unit cell = 6 $$ \times $$ $${1 \over 2}$$ = 3
Thus, formula of compound = AB3