How do i calculate the mass of a hydrometer if the density of the liquid is 0.80gcm and depth is 7.5cm?

To calculate the mass of the hydrometer, you need the volume of the liquid displaced by the hydrometer. Since the density of the liquid is 0.80 g/cm³ and the depth is 7.5 cm, the volume of the liquid displaced would be 7.5 cm³. You can then calculate the mass by multiplying the volume of liquid displaced by the density of the liquid.