How did the concentration of iodide ions change in these two trials, how did the rate change accordingly?

The concentration of iodide ions doubled.
From what was found in part a, the reaction rate increases by a factor of about 4.

All the elements are arranged by melting points on the periodic table. in row they go from metals to gasses. in the row from sodium to argon, sodium is more reactive than the one on its right, magnesium.