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Q50 (NDA-II/2019) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Applied everyday chemistry

A sample of 'soft soap' contains

Result
Your answer: —  Â·  Correct: B
Explanation

Soaps are chemically defined as the sodium or potassium salts of long-chain carboxylic acids (fatty acids) [1][2]. The physical consistency of the soap depends on the alkali metal used during the saponification process. Sodium salts of fatty acids generally produce 'hard soap', which is commonly used for solid bars [3]. In contrast, potassium salts of fatty acids produce 'soft soap' or liquid soap. These potassium-based soaps are often milder, more soluble in water, and are used in products like liquid hand soaps, shaving creams, and baby soaps. Calcium and magnesium are typically associated with water hardness and form insoluble precipitates (scum) when they react with soap, rather than being the primary constituent of the soap itself [3]. Therefore, a sample of 'soft soap' contains potassium [2].

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Activity 4.10 > p. 75
  2. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > CH COOH CH CH OH CH C C CH CH H O 3 3 2 3 2 3 2 Acid O (E - + - - - - - + thanoic acid) (Ethanol) (Ester) O > p. 73
  3. [3] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Activity 4.12 > p. 76
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SIMILAR QUESTIONS

NDA-II · 2012 · Q73 Relevance score: 0.88

Match List I (Compound) with List II (Use) and select the correct answser using the codes given below the lists. List I A. Cellulose nitrate B. Potassium sulphate C. Potassium salt of fatty adds D. Calcium oxide List II 1. Soft soap 2. Gun powder 3. Fertilizer 4. Glass Codes: ABCD ABCD

CDS-I · 2009 · Q90 Relevance score: -0.12

Assertion (A) : Soaps do not form lather with water containing salts of calcium and magnesium. Reason (R) : Calcium and magnesium salts of long-chain fatty acids are insoluble in water.

NDA-I · 2016 · Q13 Relevance score: -0.24

Soap is sodium or potassium salt of

NDA-I · 2021 · Q71 Relevance score: -1.27

Which one of the following statements about the cleansing action of soap is not true?

NDA-I · 2025 · Q71 Relevance score: -1.27

Which one of the following statements is NOT correct?