Is it 1/8 -of a delivery per hour or 1/8-of an hour per delivery

Which atom or ion is the largest? a. k b. k+ c. ca d. ca2+ e. li

May someone me with these science questions

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