What makes radioisotopes useful for dating objects? O A. They have unique emission spectra.
O B. They decay at a predictable rate.
C. Their decay products are easy to detect.
O D. They all have extremely long half-lives.

D

Explanation:

Radioactive isotopes have a definite half life that remains constant.

The percentage of the isotope left allows one to calclulate its age.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

why is arctic sea ice important? arctic sea ice keeps the polar regions cool and moderate global climate. sea ice has a bright surface; 80 percent of the sunlight that strikes it is reflected back into space. as sea ice melts in the summer, it exposes the dark ocean surface.