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)
Answer : The mole fraction of NaCl in a mixture is, 0.360
Explanation : Given,
Moles of 
= 7.21 mole
Moles of 
= 9.37 mole
Moles of 
= 3.42 mole
Now we have to calculate the mole fraction of .
Now put all the given values in this formula, we get:
Therefore, the mole fraction of NaCl in a mixture is, 0.360
