to produce 4.00l of a 250. mm solution of sodium hydroxide (naoh), how many grams of naoh must be dissolved

Iknow #2 is d. i just need to know why

Harvey mixes two liquids. which observation of the new mixture most likely indicates a precipitate is forming?

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