A balloon has equal moles of H2, N2, Cl2, and F2 gas particles. If the balloon has a total pressure of 2atm, a volume of 3L, and a temperature of 300K, how many moles of H2 gas particles are there?

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

tracks, burrows, eggshells, nests, tooth marks, or gastroliths