15 !
generally, when going down a group on the periodic table:
a. atomic radii decrease
b. ionic radii increase
c. electronegativity increases
d. reactivity decreases

- "the choice that is not an indicator of a chemical change is "state of matter changes". more common than not, chemical reactions produce energy in the form of light or heat. along with energy, they also produce a new substance called the product that could be in any state of matter (solid, gas, or liquid)."

wher is the rest of the question