Fermentation is conversion of complex organic molecules into simpler molecules by the action of enzymes. Example: Curdling of milk.

Aqueous solution of ethanol which contain 95.5% of ethanol and 4.5% of water is called rectified spirit.

If the chain contains carbon and other atoms like oxygen, nitrogen, sulphur, etc., these compounds are called heterocyclic compounds.

S. No	Soap	Detergent
i)	Soap is a sodium salt of long chain fatty acids.	Detergent is sodium salt of sulphonic acids.
ii)	The ionic part of a soap is -COO-Na+.	The ionic part in a detergent is -SO3-Na+.
iii)	It is prepared from animal fats or vegetable oils.	It is prepared from hydrocarbons obtained from crude oil.
iv)	Soaps are biodegradable.	Most of the detergents are non biodegradable.

(i) Some detergents having a branched hydrocarbon chain are not fully biodegradable by microorganisms present in water.
(ii) So they settle as insoluble chemical in water bodies.
(iii) To avoid this type of water pollution, we should. use detergents which have straight hydrocarbon chains. 
(iv) Because these are easily degraded by bacteria.

Compound	Carbon chain	Structural formula
(i) Propane	Saturated compounds open chain compounds	CH3-CH2-CH3
(ii) Benzene	Aromatic compounds in carbocyclic compounds
(iii) Cyclobutane	Alicyclic compounds contain one or more Carbocyclic compounds.
(iv) Furan	Heterocyclic compounds contains carbon and other atoms like Oxygen, Nitrogen, Sulphur, etc.,

Simplest Ketone	Structural formula
Acetone

(i) A soap molecule contains two chemically distinct parts that interact differently with water.
(ii) It has one polar end, which is a short head with a carboxylate group (-COONa) and one non-polar end having the long tail made of the hydrocarbon chain.
(iii) The polar end is hydrophilic (Water loving) in nature and this end is attracted towards water.
(iv) The non-polar end is hydrophobic (Water hating) in nature and it is attracted towards dirt or oil on the cloth, but not attracted towards water.
(v) Thus, the hydrophobic part of the soap molecule traps the dirt and the hydrophilic part makes the entire molecule soluble in water.
(vi) These forms micelles in water. The dirt is thus surrounded by the non-polar end of the soap molecules.
(vii) The charged carboxylate end of the soap molecules makes the micelles soluble in water.
(viii) Thus, the dirt is washed away with the soap.

(i) Molasses is a dark coloured syrupy liquid left after the crystallization of sugar from the concentrated sugarcane juice.
(ii) It contains 30 % of sucrose, which cannot be separated by crystallization
(i) Dilution of molasses: Molasses is first diluted with water to bring down the U concentration of sugar to about 8 to 10%.
(ii) Addition of Nitrogen source:
a) Molasses usually contains enough nitrogenous matter to act as food for yeast during the fermentation process.
b) If the nitrogen content of the molasses is poor, ammonium sulphate or ammonium phosphate is added.
(iii) Addition of Yeast:
a) This solution kept in large fermentation tank and yeast is added to and it kept at about 303 K for a few days.
b) During this period, the enzymes invertase and, zymase present in yeast, converts sucrose into ethanol.

c) The fermented liquid is technically called wash.
(iv) Distillation of wash:
a) This wash containing 15 to 18 % alcohol, is now subjected to fractional distillation.
b) The main fraction drawn in an aqueous solution of ethanol which contains 95.5 % of ethanol and 4.5 % of water.
c) This is called rectified spirit.
d) This mixture is then refluxed over quicklime for about 5 to 6 hour and then allowed to stand for 12 hours.
e) On distillation of mixture, pure alcohol (100%) is obtained.
f) This is called absolute alcohol.

Homologous series is a group or a class of organic compounds having same general formula and similar chemical properties in which the successive numbers differ by a -CH₂ group.
E.g: Methane - CH₄
Ethane - CH₃CH₃
Propane - CH₃CH₂CH₃
Characteristics:
(i) Each member of the series differs from the preceding or succeeding member by one methylene group (-CH₂) and hence by a molecular mass of 14 amu.
(ii) All members of a homologous series contain the same elements and functional group.
(iii) They are represented by a general molecular formula. e.g. Alkanes, CnH_{2n + 2}
(iv) All the members can be prepared by a common method.

(i) 
(ii) IUPAC name - Butane-2-ol (or) 2-Butanol.
(iii) The compound is saturated, because these compounds are do not decolourize with bromine water.