What is the molar mass of: Pb(NO3)2

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

For ai it's atomic number is 13 and it's mass number is 27 how many neutrons does it have

Which of the following is true about the speed of light? it depends on the wavelength.