commercial scuba divers use tanks filled with a mixture of gases known as trimix on very long, deep dives. Trimix is composed of 70 percent nitrogen, 10 percent oxygen, and 20 percent helium. The total pressure of trimix inside a certain tank at the beginning of a dive is 118.4atm.

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

< > according to newton's third law of motion, forces always act in equal but opposite pairs. another way of saying this is for every action, there is an equal but opposite reaction.< >