He nfipa 704 system uses a numerical value between and to indicate the level of hazard for that particular chemical.

The NFPA 704 system is much more known as the fire diamond. This system is for Standard System for the Identification of the Hazards of Materials for Emergency Response. The numbers used in the diamond ranges from 0 to 4. The 0 is used when the condition brings minimal hazard, while number 4 is used for hazardous materials.

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃  → 3 nicl₂ + 2 albarium and copper bromideba + cubr  →  no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al  → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn  → znso₄ + na