If litmus paper is dipped in a very acidic and then in a basic what will happen

Which type of bond is present in hydrogen sulfide (h2s)? the table of electronegativities is given. a. hydrogen b. ionic c. nonpolar covalent d. polar covalent

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

Can someone me with questions 15 to 17 plz.