Organic Chemistry B. Alcohol

1. Ethyl alcohol is made unfit for drinking by the addition of the following: [R.A.S./R.T.S.(Pre) 1999]

(a) Potassium Cyanide
(b) Methanol and Pyridine
(c) Acetic acid and Pyridine
(d) Naphthalene

Correct Answer: (b) Methanol and Pyridine

Solution:Ethyl alcohol becomes poisonous by the addition of methanol and pyridine.

2. The offending substance in the liquor tragedies leading to blindness etc. is – [I.A.S. (Pre) 1996]

(a) Ethyl alcohol
(b) Amyl alcohol
(c) Benzyl alcohol
(d) Methyl alcohol

Correct Answer: (d) Methyl alcohol

Solution:Methyl alcohol is a colorless liquid. It is soluble in water. Its smell is like a pungent, unpleasant and intensive flavour. In each ratio, it is poisonous while in excess, the intake of methyl alcohol results in madness, blindness and its excess consumption can also cause death.

3. Which one of the following is also known as "wood spirit"? [U.P.P.C.S. (Mains) 2015]

(a) Methyl alcohol
(b) Ethyl alcohol
(c) Ethylene glycol
(d) Glycerol

Correct Answer: (a) Methyl alcohol

Solution:Methyl alcohol (CH₃OH) is also called wood spirit. It is obtained by the destructive distillation of wood.

4. Fermentation of sugar leads to – [47th B.P.S.C. (Pre) 2005]

(a) Ethyl alcohol
(b) Methyl alcohol
(c) Acetic acid
(d) Chlorophyll

Correct Answer: (a) Ethyl alcohol

Solution:Ethyl alcohol is formed by the fermentation of sugar, which is made of glucose and fructose.

5. Glucose is converted to ethyl alcohol by the enzyme – [66th B.P.S.C. (Pre) 2020]

Correct Answer: (c) zymase

Solution:Glucose is converted to ethyl alcohol (ethanol) by the enzyme zymase. Zymase catalyzes the fermentation of sugar (glucose and fructose) into ethanol and carbon dioxide. This enzyme complex naturally occurs in yeast and other anaerobic organisms. This enzyme is used in the preparation of ethanol and alcoholic beverages commercially. Invertase enzyme converts sucrose (cane sugar) into glucose and fructose. Maltase enzyme converts maltose into glucose while diastase enzyme converts starch into maltose.

6. To whom molasses are excellent raw material for production? [Chhattisgarh P.C.S. (Pre) 2005]

(a) Glycerin
(b) Urea
(c) Alcohol
(d) Paraffin

Correct Answer: (c) Alcohol

Solution:Liquor or alcoholic beverages are prepared by fermentation of different substances like molasses, etc. The percentage of alcohol also varies in them. Beer, Champagne, Cider, Port and Sherry, Brandy, Whisky, Rum, Gin etc. are some types of liquors.

S. No.	Name	Alcohol %	Raw Material
1	Rum	45 to 55%	Molasses
2	Brandy	40 to 50%	Grapes
3	Whisky	40 to 50%	Barley, Corn
4	Beer	3 to 6%	Barley
5	Champagne	10 to 15%	Grapes
6	Cider	2 to 6%	Apple

7. Alcohol that is derived from fermentation of germinated barley grains is known as: [U.P. R.O./A.R.O. (Mains) 2016]

(a) Beer
(b) Wine
(c) Vodka
(d) Rum

Correct Answer: (a) Beer

Solution:Beer is usually derived from the fermentation of malt derived from the digestion of germinated barley grains. Barley, water, hops and yeast are the four magic ingredients that are required for making beer. Other grains like maize, rice, rye, and wheat are also used in making beer. Whisky is also made from fermented barley grains.

8. The breath test conducted by police to check drunken driver has which one of the following on the filter paper? [66th B.P.S.C. (Pre) 2020]

(a) Potassium dichromate-sulfuric acid
(b) Potassium permanganate-sulfuric acid
(c) Silica gel coated with silver nitrate
(d) Turmeric
(e) None of the above/More than one of the above

Correct Answer: (a) Potassium dichromate-sulfuric acid

Solution:The breath test conducted by police to check drunken driver through old breathalyzer has potassium dichromate-sulfuric acid on the filter paper. When alcohol vapor makes contact with the orange dichromate coated crystals, the color changes from orange to green due to oxidation of alcohol into acetic acid. The degree of the color change is directly related to alcohol level in the breath.