Which group of diamagnetic transition metals trends in density and melring points that don't match the same trends seen in the groups?

Ab c or d ? i’m not sure what the answer is

What is the chemical formula for the compound formed between sodium and flour one

The comparison of the number of atoms in a copper coin the size of a penny with the number of people on earth is made to illustrate which of the following? a. that atoms are indivisible b. that atoms are very small c. that atoms are very large d. that in a copper penny, there is one atom for every person on earth