A 4.0 kg cylinder of solid iron is supported by a string while submerged in water. The density of iron is 7860 kg/m³ and that of water is 1000 kg/m³.

a) Find the buoyant force the water exerts on the iron cylinder. b) Find the tension in the string. c) When the iron cylinder is completely submerged in liquid with unknown density, the tension in the string is 32 N. Find the density of the liquid.

Express your answer with the appropriate units.