# A compound made up of A and B atoms have a crystalline structure ,in which A forms Hexagonal close packed structure and B occupies $\;\large\frac{2}{3}\;$ of octahedral holes .What will be the simplest molecular formula ?

$(a)\;A_{3}B_{3} \qquad(b)\;A_{2}B_{3} \qquad(c)\;A_{3}B_{2} \qquad(d)\;A_{4}B_{3}$

Answer : $A_{3}B_{3}$
So molecular formula will $\;A_{6}B_{\large\frac{6 \times 2}{3}}=A_{6}B_{4}=A_{3}B_{2}\;$