7. (a). The standard kilogram is a platinum-iridium cylinder 39 mm in height and 39 mm in diameter. What is the density of the material? (b). Acceleration due to gravity is given as 9.8m/s2. What is its value in mm/ps2? (c). A liquid has a density of 6 kg/m3. What is the density of the liquid in g/mm3? (d). The density of lead is 11.3 ��њ3. What is this value in kilograms per cubic meter?