Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and non-metals take part in displacement reactions. Example : Reaction of iron nails with copper sulphate solution.
Dissolution means to make the compound apart, So when we have ionic compounds like NaI which has metal and non-metal ions, It separates into parts of positive ions and negative ions. After we separate this compound apart we will put the charge of each on above its symbol and then start to balance the equation of the dissolution.
So the dissolution equation of NaI is:
NaI(s) → Na^+(s) + I^-(Aqu)
3.815 that's the awnser......................................
A polar molecule is when the arrangement of the atoms in molecules are unequal where one end of the molecule has a positive charge while the other end has a negative charge. Examples of a polar molecule are water, ammonia, hydrogen sulfide and sulfur dioxide. The opposite is called a nonpolar molecule.