The reaction for magnesium iodide when put into water is as below
MgI2(s) → Mg^2+(aq) + 2I^-(aq)
when magnesium iodide but into water it dissociate/ ionize completely into Mg^2+ and 2l^- ions. Magnesium iodide dissociate/ionize completely because magnesium iodide is a strong electrolyte which dissociate/ ionize completely into their ions when it is put into water .
Al is 1. As for NO3,it is one entity, an the whole thing is being multiplied by 3. Use the distributive property from math. N is 3. And O is 9. In total, there are 13 atoms.
