If three elements P, Q and R crystallise in a cubic unit cell with P atoms at the corners, Q atoms at the cubic centre and R atoms at the centre of each face of the cube, then write the formula of the compound.

Explanation

To determine the formula of the compound formed by elements P, Q, and R in a cubic unit cell, we can follow these steps:

### Step 1: Identify the positions of the atoms
- **P atoms** are located at the corners of the cubic unit cell.
- **Q atoms** are located at the center of the cubic unit cell.
- **R atoms** are located at the center of each face of the cube.

### Step 2: Calculate the contribution of P atoms
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