Engineering Chemistry Questions and Answers – Soaps

This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Soaps”.

1. Soaps are _____________ based soapy detergents.
a) Water
b) Kerosene
c) Oil
d) Acid
View Answer

Answer: c
Explanation: Soaps are oil based soapy detergents. Soaps for cleansing are obtained by treating vegetable or animal oils and fats with a strongly alkaline solution.

2. The saponification of a fat or oil is done using _______________ solution for hot process.
a) KOH
b) NaOH
c) HCl
d) NaCl
View Answer

Answer: b
Explanation: The saponification of a fat or oil is done using NaOH solution for hot process. Saponification to the sodium salt of myristic acid takes place with NaOH in water. NaOH gives hard soaps.

3. The saponification of a fat or oil is done using _______________ solution for cold process.
a) KOH
b) NaOH
c) HCl
d) NaCl
View Answer

Answer: a
Explanation: The saponification of a fat or oil is done using KOH solution for cold process. When potassium hydroxide (KOH) is used, a soft soap is formed. It cannot be used in hard water.
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4. Soft soaps are the limitation of hot process because of their ____________
a) High alkalinity
b) Low alkalinity
c) Low solubility in water
d) High solubility in water
View Answer

Answer: d
Explanation: Soft soaps are the limitation of the hot process because of their greater solubility in water. When potassium hydroxide (KOH) is used, a soft soap is formed by the cold process. It cannot be used in hard water.

5. Select the incorrect statement from the following option.
a) Hard soaps are the sodium carboxylates
b) Soft soaps are potassium carboxylates
c) Hard soaps are manufactured by cold process
d) Example of soft soap – shampoo and shaving cream
View Answer

Answer: c
Explanation: Hard soaps are manufactured by hot process and soft soaps are manufactured by cold process.
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6. Which of the following is the residual product in the formation of soap?
a) Glyceraldehyde
b) Glycerol
c) Glycerine
d) Acrylonitrile
View Answer

Answer: b
Explanation: Glycerol is the residual product in the formation of soap. The immediate product is called an orthoester:

7. Which of the following is a typical soap molecule?
a) Calcium stearate
b) Potassium permanganate
c) Sodium bicarbonate
d) Sodium stearate
View Answer

Answer: d
Explanation: Sodium stearate is a typical soap molecule. Sodium stearate is the sodium salt of stearic acid. Sodium stearate has both hydrophilic and hydrophobic parts, the carboxylate and the long hydrocarbon chain, respectively.
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8. Select the correct statement from the following options.
a) The soap micelle is unstable due to positive charge on its head
b) The soap micelle is stable due to positive charge on its head
c) The soap micelle is unstable due to negative charge on its head
d) The soap micelle is stable due to negative charge on its head
View Answer

Answer: d
Explanation: The soap micelle is stable due to the negative charge on its polar head. It carries a negative charge due to attractive forces.

9. Soaps do not act efficiently in hard water and in acidic solution.
a) True
b) False
View Answer

Answer: a
Explanation: Soaps do not act efficiently in hard water and in acidic solution due to their softness as compared to detergents. Soaps are the soft detergents and cannot be used in water containing calcium and magnesium salts.
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Sanfoundry Global Education & Learning Series – Engineering Chemistry.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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