Correlate the items listed in Column I with those listed in Column II.
| Column I | Column II |
| A. Synthesis gas | 1. Na2[Na4(PO3)6 ] |
| B. Heavy water | 2. Mixture of CO and H2 |
| C. Calgon | 3. Prolonged electrolysis of water |
| D. Salt like hydrides | 4. Stoichiometric compounds of s-block elements |
Codes
| A | B | C | D | |
| 1. | 4 | 3 | 2 | 1 |
| 2. | 2 | 3 | 1 | 4 |
| 3. | 1 | 4 | 3 | 2 |
| 4. | 4 | 1 | 3 | 2 |
