Question

Atom of b for hcp lattice and those of the element a occupy two third of tetrahedral void

Answer 1

Let the number of atoms of B is x.
Then , the no. of tetrahedral voids is 2x.
No. of atoms of A is 2 × (2x) / 3 = 4x/3
Ratio A : B
4x/3 : x = 4 : 3
therefore , formula of compound is A4B3

Answer 2

$\huge\boxed{\underline{\mathcal{\red{A}\green{N}\pink{S}\orange{W}\blue{E}\purple{R}}}}$

• ❤.. The number of tetralhedral voids formed is equal to twice the number of atoms of element B and only 2/3rd of these are occupied by the atoms of element A.
• ❤..Hence the ratio of the number of atoms of A and B is ${2×(2/3):1 or 4:3}$ and the formula of the compound is ${A4B3}$.