4. On the average, each person in the United States produces over 20 tons of CO2 each year, and collectively this country produces 25 percent of all CO2 released into the
atmosphere worldwide. How can people or industries help reduce our contribution to
this global problem? What are some ways you could reduce your own energy use?

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6

thats a little if u want the answer just look it up on google thats what i do haha : )

16

explanation:

the marks go by 4s