In ZnS structure , Sulphate ions occupy all the lattice points while Zn2+ ions are present in alternate tetrahedral voids.

Explanation:

Crystal lattice:
A crystal lattice is a repeating three-dimensional pattern of atoms, ions, or molecules in a solid. It represents the arrangement of particles in a crystal structure.

Tetrahedral void:
A tetrahedral void is a space between four atoms or ions arranged in the shape of a tetrahedron.

Occupation of tetrahedral void:
In some crystal lattices, the tetrahedral voids may be occupied by atoms or ions. The occupation of tetrahedral voids depends on the size and charge of the atoms or ions involved.

Now let's analyze the occupation of tetrahedral voids in the given crystal lattices:

a) NaCl:
In the crystal lattice of NaCl, the sodium (Na+) ions occupy the face-centered cubic lattice points, and the chloride (Cl-) ions occupy the octahedral voids. There are no tetrahedral voids in the NaCl crystal lattice, so the answer is not option 'A'.

b) ZnS (Blend):
In the crystal lattice of ZnS (Blend), the zinc (Zn2+) ions occupy the face-centered cubic lattice points, and the sulfur (S2-) ions occupy the tetrahedral voids. Therefore, in ZnS (Blend), the tetrahedral voids are occupied. Hence, the correct answer is option 'B'.

c) ZnS (wurtzite):
In the crystal lattice of ZnS (wurtzite), the zinc (Zn2+) ions occupy the hexagonal close-packed lattice points, and the sulfur (S2-) ions occupy the tetrahedral voids. Therefore, in ZnS (wurtzite), the tetrahedral voids are occupied. However, this option is not the correct answer, as the correct answer is option 'B'.

d) Na2O:
In the crystal lattice of Na2O, the sodium (Na+) ions occupy the face-centered cubic lattice points, and the oxygen (O2-) ions occupy the octahedral voids. There are no tetrahedral voids in the Na2O crystal lattice, so the answer is not option 'D'.

Conclusion:
The correct answer is option 'B' because in the crystal lattice of ZnS (Blend), the tetrahedral voids are occupied.