Carbonic acid (H2CO3) forms when carbon dioxide (CO2) dissolves in water according to this equation:
CO2 + H2O
H2CO3
How many moles of CO2 must dissolve in excess water to produce 12 moles of
H2CO3?
Enter your answer as a number only; no units.

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