The usual disease caused by the excessive drinking of alcohol over a long period of time is:

62 The chemical which is not required for the preparation of soap in the laboratory is: 63 Which of the following can damage optic nerve leading to blindness, if taken internally? 65 Which of the following molecular formula corresponds to ethyl butanoate ester? 66 A neutral organic compound X of molecular formula C₂H₆O on oxidation with acidified potassium dichromate gives an acidic compound Y. Compound X reacts with Y on warming in the presence of cone. H₂SO₄ to give a sweet smelling substance Z. What are X, Y and Z?