Question

A solid has a structure in which W atoms are located at the corners of a cubic lattice, O atoms at the centre of edges and Na atoms at the centre of the cube. The formula of the compound is ______.

Options

• NaWO₂

• NaWO₃

• Na₂WO₃

• NaWO₄

Answer 1

A solid has a structure in which W atoms are located at the corners of a cubic lattice, O atoms at the centre of edges and Na atoms at the centre of the cube. The formula of the compound is NaWO₃.

Explanation:

W atoms at the 8 corners of a cubic unit cell

O atoms at the 12 edges

Na atom at the centre of the cube

We have to find the formula of the compound.

∴ W atoms at 8 corners: 

Each corner is shared by 8 unit cells = `8 xx 1/8 = 1` atom of W

∴ O atoms at 12 edges:

Each edge is shared by 4 unit cells = `12 xx 1/4 = 3` atom of O

∴ Na atom at the centre:

The body-center is fully inside the unit cell = 1 × 1 = 1 atom of Na

∴ The formula of the compound is NaWO₃.