Tiana is a chemist who is making a chemical to add to swimming pools in order to make the water safer. she mixed two solid substances together in a sealed container. the diagram above shows the repeating groups of atoms that make up the two starting substances. After mixing, Tiana found two liquid substances in the sealed container. (Nothing had escaped.) Which of the diagrams to the left shows the repeating groups of atoms that make up the ending substances? ​

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

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

i'm pretty sure it is letter c.) car