20. Periods are
and represent the number of
in the electron configuration

Which supports the idea that birds and butterflies both have wings but they do not have a common ancestor with wings? a. the wings are analogous structures that evolved differently and do not have a similar internal structure. b. the wings are homologous structures that evolved differently and do not have a similar internal structure. c. wings of birds are vestigial structures, but the wing structures of bats are not vestigial. d. wings of bats are vestigial structures, but the wing structures of birds are not vestigial

How manyatoms of mercury are in 1.4214e+1 ml sample

How many moles of magnesium is 3.01 x10^22 atoms of magnesium?