A solid is made of two element P and Q. Atoms P are in ccp arrangement and atoms Q occupy all the octahedral voids and half of the tetrahdedral voids, then the simplest formula of the compound is
| A. |
`PQ_2` |
 |
| B. |
`P_2Q` |
| C. |
PQ |
| D. |
`P_2O_2` |
Four atoms P contributes to one unit cell from ccp arrangement and 4 atoms Q from the all octahedral voids and 4 atoms Q from the half of the tetrahedral void contributes one unit cell. So, formula of solid is `P_4O_8` so, the simplest formula of the solid is `PQ_2` .