4. Two liquids at the same temperature are mixed together. You observe no change in color and no gas or solid formed. Which of
the following would you check to see if a chemical change may have occurred ?

I would say you would check for temperature change. A chemical reaction is shown by a change in color, a change in temperature, solids forming, odor, or smoke. So check temperature.

edit: while odor is an option in the answer. i think temp is a better choice.

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

14,16 18 reacts with group