The given table shows some properties of four substances P, Q, R and S.
Study the table carefully and identify P, Q, R and S.
| P | Q | R | S | |
| A | Sodium | Iron | Gold | Copper |
| B | Calcium | Aluminium | Phosphorus | Gold |
| C | Potassium | Zinc | Graphite | Aluminium |
| D | Sodium | Magnesium | Copper | Iron |