While the other pairs, sodium and potassium are the metals, nitrogen and iodine, chlorine and bromine, helium and oxygen are the non-metals. They do not form ionic bond. Hence, the correct pairs of elements likely to form ionic compounds are, potassium and sulfur, magnesium and chlorine
The better era tbh.......
No, molecules don’t ever stop moving
We subtract the enthalpies of the reactants from that of the products:

Since this is < 0, this is an exothermic reaction.
I do believe it’s C if I’m wrong Myb fam