What is the mass of 3.21 x 1021 molecules of dinitrogen tetroxide?

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

1) these are barrel shaped microtubules in most animal cells, that organize the spindles during cell division

Which type of substance ionizes partially and gives off hydrogen ions when dissolved in water? a. strong acid b. strong base c. weak acid d. weak base