The correct answer would be option 3. I order for a single displacement to occur there must be a single element and one compound. From then, the single element will then swap places with one of the elements in the compound (or in this case single circle and combined circles). Hope this helped!
i think its theory but im not to sure
Answer:
See below
Explanation:
Ammonium 
is not a molecular ion because it is just a poly-atomic ion. A molecular ion has a "negative or positive charge" as a whole but the positive charge on here is not on the whole. So, it is a poly-atomic ion and not molecular ion.
The answer is (2). Heat always flows down the temperature gradient, from high temperature to low temperature. Therefore, since the person is the warmest, heat flows from the person to both the ice and the air. Additionally, since the air is warmer than the ice, heat flows from the air to the ice.
