What is the common name of a biological sedimentary rock composed of microcrystalline silica (SiO2) originally formed as shells of living diatoms and radiolarian plankton, compressed into hard, flaky rock that can be used to make tools

In november 1987, a massive iceberg broke loose from the antartic ice mass and floated free in the ocean. the chunk of ice was estimated to be 98 mi long, 25 mi wide, and 750 ft thick. a typical backyard swimming pool contains about 24,000 gallons of water. how many of these pools could you fill from the water in this iceberg? (assume the iceberg is a rectangular solid of the above dimensions and consists of water only). express answer in scientific notation.