Does anyone know how to solve questions 6 and 7? if so could you show me how to do it

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

Joan writes four numbers on the board in standard form, and then she writes their scientific notation

Which of the following natural processes is most likely to support the formation of an underwater sinkhole? a pollution buildup from deposited minerals b limestone cave collapsing due to changes in sea level c erosion of large amounts of sand moved by ocean waves d oxidation of rock formed by chemical weathering