Incorrect Statement about Soaps:

Statement a: Soaps are acidic in nature.

Soaps are actually alkaline in nature, not acidic. They are made by the saponification reaction, which involves the hydrolysis of fats and oils. During this reaction, triglycerides (fats and oils) are broken down into glycerol and fatty acid salts (soaps). The fatty acid salts have an alkaline pH, typically around 9-10.

Soaps are effective at cleaning because they have both hydrophilic (water-loving) and hydrophobic (water-repelling) properties. The hydrophilic end of the fatty acid salt molecule attracts water molecules, while the hydrophobic end attaches to dirt, oil, and grease. This allows the soap to lift away these substances from surfaces and rinse them away with water.

Correct Statements about Soaps:

Statement b: (C17H31COO)2Ca is the scum produced when the soap reacts with ions present in hard water.

When soap reacts with the ions present in hard water, it forms scum. The scum is composed of insoluble compounds, such as calcium and magnesium salts of fatty acids. (C17H31COO)2Ca is an example of a calcium salt of a fatty acid, which can contribute to the formation of scum in hard water.

Statement c: C17H31COONa is a soap.

C17H31COONa is the chemical formula for sodium stearate, which is a common soap. Soaps are typically made by reacting fatty acids with an alkali, such as sodium hydroxide (NaOH) or potassium hydroxide (KOH). The resulting product is a salt of the fatty acid, which is the soap.

Statement d: Fat is hydrolyzed with NaOH to get soap.

To produce soap, fats and oils are hydrolyzed (broken down) by reacting them with a strong base, such as sodium hydroxide (NaOH) or potassium hydroxide (KOH). This reaction is called saponification. The triglycerides in fats and oils are broken down into glycerol and fatty acid salts (soaps) when they react with the base.

During the saponification process, the base (NaOH or KOH) reacts with the ester bonds in the triglycerides, resulting in the formation of glycerol and the corresponding fatty acid salts. These fatty acid salts are the soaps that have cleansing properties.

Overall, the incorrect statement about soaps is option 'A' - Soaps are acidic in nature. Soaps are actually alkaline in nature with a pH around 9-10.