I suppose you mean to ask why we can't go through obstacles.
Any atom is surrounded by an electronic cloud. When two atoms get close to each other, the electronic clouds repel each other, preventing them from interpenetrating each other. That same phenomenon, on a larger scale, prevents us from going through matter.
Explanation:
An ionic equation will be the one in which all the participating species will be present as ions.
The given reaction will be as follows.
Balancing this equation by multiplying 
by 2 and 
by 3 on reactant side. Whereas multiply KBr by 6 on product side.
Hence, the net ionic equation will be as follows.
As both 
and 
are spectator ions. Hence, the net ionic equation will be as follows.
Answer:
law of independent assortment
Salt dissolving into water is a physical change because it can be reversed as in chemical change cannot be reversed as in you can boil water and have the salt on the bottom
