Atoms of elements `B` from hep lattice and those of element `A` occupy two-thirds of tetrahedral voids. What is the formula of the compound formed by elements `A` and `B`?

Explanation

To find the formula of the compound formed by elements A and B, we need to analyze the information given in the question step by step.

### Step 1: Determine the number of atoms of element B in the HCP lattice.
- In a hexagonal close-packed (HCP) lattice, the number of atoms can be calculated as follows:
- There are 12 corner atoms, each contributing \( \frac{1}{6} \) of an atom.
- There are 3 atoms at the body centers, each contributing 1 atom.
- There are 2 face-centered atoms, each contributing \( \frac{1}{2} \) of an atom.

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