Final answer:
The relative density of a substance is the ratio of its density to the density of water. Without additional information, the relative density of the solid cannot be calculated. The relative density of the liquid is inferred to be 0.75, based on the described behavior of a hydrometer with that density.
Step-by-step explanation:
The relative density, also known as specific gravity, is the ratio of the density of a substance to the density of a reference substance, typically water for liquids and solids. When calculating relative density of a solid or a liquid, we use the formula:
Relative Density = Density of Substance / Density of Water
where the density of water is taken as 1 g/cm³ or 1 g/mL.
To calculate the relative density of the solid given its weight in liquid (apparent weight) as 170 gf (where gf represents gram-force), we need additional information, such as the actual weight of the solid in air and the weight of the equivalent volume of water. However, with the data provided, we cannot compute the relative density of the solid.
For the liquid, given the density of the hydrometer (0.750 g/mL) and that it floats with 92.0% of its volume submerged, we can deduce that the relative density of the liquid is 0.75. This is because the weight of the displaced liquid must be equal to the weight of the submerged part of the hydrometer for it to float. Since the hydrometer's density is 0.750 g/mL, the density of the liquid must be the same for 92.0% of its volume to be submerged.