The pairs are:
K, Kr - Same period
Be, Mg - Same group
Ni, Tc - Both are transition metals
B, Ge - Both are metaloids
Al, Pb - Both form inert oxides
B. A gram would have a lot more molecules of propane than a mole
This allows us to visually see the structure of the atoms/ molecules so we can get a better understanding of what they look like.
