A spherical steel ball has a mass of 3.475 g and a diameter of 9.40 mm. what is the density of the steel? ( The volume of a sphere is where r is the radius)

Achemistry student weighs out 0.306 g of citric acid (h3c6h5o7), a triprotic acid, into a 250 ml volumetric flask and dilutes to the mark with distilled water. he plans to titrate the acid with 0.1000 m naoh solution. calculate the volume of naoh solution the student will need to add to reach the final equivalence point. be sure your answer has the correct number of significant digits.