Yes it could, but you'd have to set up the process very carefully.
I see two major challenges right away:
1).  Displacement of water would not be a wise method, since rock salt 
is soluble (dissolves) in water.  So as soon as you start lowering it into 
your graduated cylinder full of water, its volume would immediately start 
to decrease.  If you lowered it slowly enough, you might even measure 
a volume close to zero, and when you pulled the string back out of the 
water, there might be nothing left on the end of it.
So you would have to choose some other fluid besides water ... one in 
which rock salt doesn't dissolve.  I don't know right now what that could 
be.  You'd have to shop around and find one.
2).  Whatever fluid you did choose, it would also have to be less dense 
than rock salt.  If it's more dense, then the rock salt just floats in it, and 
never goes all the way under.  If that happens, then you have a tough 
time measuring the total volume of the lump.
So the displacement method could perhaps be used, in principle, but 
it would not be easy.
        
             
        
        
        
There will be chemical reaction(equation4Na+02--2Na20
        
             
        
        
        
Milk is colloid while soil and water is a heterogeneous mixture and is a suspension mixture.
        
                    
             
        
        
        
Answer:
The chemical equation needs to be balanced so that it follows the law of conservation of mass.
Explanation: