1. Which one of the following is used in the manufacture of soaps?
(a) Vegetable oil
(b) Mobil oil
(c) Kerosene oil
(d) Cutting oil
[44th B.P.S.C. (Pre) 2000]
Ans. (a) Vegetable oil
- Soap is made of animal or plant fat mixed with a strong alkaline substance called caustic soda.
- When mixed with water, it breaks dirt off surfaces.
- Soap makers usually use processed fat that is made into fatty acids to avoid impurities and make water as a by-product instead of glycerine.
- Many types of vegetable fats such as olive oil, palm kernel oil, and coconut oil are also used in making soap.
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2. Soap, remove grease by –
(a) Coagulation
(b) Adsorption
(c) Emulsification
(d) Osmosis
(e) None of the above/More than one of the above
[60th to 62nd B.P.S.C. (Pre) 2016]
Ans. (c) Emulsification
- Emulsifiers are usually made up of long molecules that have polar parts, such as soap.
- Soap molecules contain two parts, a long carbon chain that is soluble in fat, and a water-soluble polar part (COO– Na+).
- During emulsification, the soap’s dipolar, alkaline part dissolves oil or grease, and the polar part mixes with the water.
- When mixed together, the grease is suspended in the water in tiny droplets and can flow smoothly with the water.
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3. What is detergent?
(a) Soap
(b) Medicine
(c) Catalyst
(d) Refining agent
[40th B.P.S.C. (Pre) 1995]
Ans. (d) Refining agent
- Detergents are not the same as soap.
- They are made with special chemicals called surfactants which help to clean and refine things.
- Detergent usually refers to the powder or liquid you use to do the dishes or laundry, not the soap you use to wash your hands.
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4. Detergents used for cleaning clothes are :
(a) Carbonates
(b) Bicarbonates
(c) Bismuthates
(d) Sulfonates
(e) None of the above/More than one of the above
[63rd B.P.S.C. (Pre) 2017]
Ans. (d) Sulfonates
- Cleaning detergents for clothes usually contain substances that are similar to soap but can dissolve better in hard water.
- These substances are called alkylbenzene sulfonates.
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5. Assertion (A): Detergent easily removes oil and dirt from dirty garments.
Reason (R): Detergent increases the surface tension of water.
Code :
(a) Both (A) and (R) are true and (R) is the correct explanation of (A)
(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true.
[U.P.P.C.S. (Pre) 1997]
Ans. (c) (A) is true but (R) is false
- A statement that detergent can easily get rid of oil and dirt from clothing is true.
- Soap or detergent molecules stick to the surface of the water, which weakens the bond between water molecules and causes the surface tension to decrease.
- Therefore, the statement is true, but the other part is false.
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6. Assertion (A): Synthetic detergents can make more lather in hard water.
Reason (R): Synthetic detergents form soluble calcium and magnesium salts with hard water.
(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true.
[I.A.S. (Pre) 2002]
Ans. (a) Both (A) and (R) are true and (R) is the correct explanation of (A).
- Soap and detergent are not the same.
- Detergent is used to clean clothes when the water is hard, meaning it has a lot of calcium and magnesium in it.
- Detergent doesn’t make a solid when combined with these minerals, so it produces more foam and can remove dirt and oil from clothes.
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7. Consider the following statements? Sodium silicate and sodium sulfate are mixed as detergents in washing powders so that–
1. To maintain the dryness of the powder.
2. To maintain the basicity of powder.
Which of the following statements is correct?
(a) only 1
(b) only 2
(c) both 1 & 2
(d) None of both
[I.A.S. (Pre) 2003]
Ans. (c) both 1 & 2
- Adding sodium sulfate to the washing powder increases its alkalinity.
- The sodium silicate makes the powder crystalline so that it can remain in a dry form.
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