What is the ionic bond of magnesium chloride?

As you move from right to left on the periodic table the atomic radius fill in the blank

1. combine iron and copper (ii) sulfate solution. (hint: iron will form the iron (iii) ion) fe + cuso4 → 2. combine lead (ii) nitrate and potassium iodide solutions. pb(no3)2+ kl → 3. combine magnesium metal and hydrochloric acid solution. mg + hcl → 4. electrolysis (splitting) of water. h2o → 5. burning magnesium. mg + o2 →

How could a student test the effect of removing heat from a gas that is stored in a sealed container? what must occur in order for matter to change states?