Ordinary soaps when treated with hard water, precipitate as salts of calcium and magnesium. They appear at the surface of the cloth as sticky grey scum. Thus the soaps cannot be used conveniently in hard water.

Water that contains calcium and magnesium ions is said to be hard water.

Ketones
(i) It is used as solvent
(ii) Stain remover

Decarboxylation means removal of CO₂

On cooling, pure ethanoic acid is frozen to form ice like flakes. They look like glaciers, so it is called glacial acetic acid.

Its molecular formula is C₂H₄O₂. Its structural formula is CH₃COOH.

Dehydrogenation: When the vapour of ethanol is passed over heated copper catalyst at 573K, it is dehydrogenated to acetaldehyde.

Reaction of an alcohol with a carboxylic acid gives a compound having fruity odour. This compound is called as an ester and the reaction is called esterification.
Example:

The nitrogen content of the molasses fortified by the addition of ammonium sulphate or ammonium phosphate.

Molasses is a dark coloured syrupy liquid  left after the crystallization of sugar from the concentrated sugarcane juice

(i) Unsaturated compounds like alkenes decolourize bromine water.
(ii) Saturated compounds like alkanes do not decolourize bromine water

(i) Yes
(ii) Furan

(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.

Ethanoic acid is prepared by the oxidation of ethanol in the presence of alkaline potassium permanganate or acidified potassium dichromate.