(a) a few drops of strongly smelling eucalyptus oil was treated with vinegar.
(b) the rain water mixing with river water was found to be having pH less than 7.
(c) sonal brushes her teeth with the best quality toothpaste everyday.
(d) electrolysis is carried out on sodium chloride solution.
(e) copper sulphate is heated.
(a) Vinegar is an acid strong odour of eucalyptus oil remain as it is in acid.
(b) That means river water is acidic in nature and it will damages to those who drink it or destroys the plants and bushes come in contact with it.
(c) The toothpastes contains substance basic in nature. The food particles in the mouth are degraded by bacteria to produce acid with pH below 6. Base in toothpaste neutralizes the same.
(d) Sodium is deposited at cathode and Cl2 gas is liberated at anode.
(e) Copper sulphate looses water molecule on heating these water molecules are known as water of crystallization and we get anhydrous copper sulphate.