A0.8kg object displaces 500ml of water what is its specific gravity

Specific gravity is the ratio of density of substance and density of water

We know that density of water = 1 g /mL at standard conditions

now as given that the 0.8 Kg of the substance / object is able to displace 500mL of water , it means that

Mass of object = 800g

The volume occupied by 800g of object = 500 mL

Density = mass / volume

Density of object = 800 / 500= 1.6 g / mL

The specific gravity of object = density of object  / density of water = 1.6 / 1 = 1.6 (no units)