Soaps & Detergents — Homi Bhabha Exam Chemistry MCQs with Solutions
Free Homi Bhabha Exam Chemistry Soaps & Detergents MCQs with step-by-step solutions (5 questions). Part of Substances in Daily Use & Applied Chemistry. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Soaps & Detergents · medium · theory
Soap is chemically the sodium or potassium salt of:
A. nitric acid
B. carbonic acid
C. long-chain fatty acids ✓ Correct
D. mineral acids
Solution: Soaps are sodium/potassium salts of long-chain fatty acids.
Q2 — Soaps & Detergents · hard · theory
Soap molecules remove oily dirt by forming tiny clusters called:
A. polymers
B. ions
C. micelles ✓ Correct
D. crystals
Solution: The soap tails dissolve in oil while the heads face water, forming micelles that lift dirt away.
Q3 — Soaps & Detergents · hard · theory
Soaps do not form a good lather with hard water because hard water contains:
A. excess soap
B. no minerals
C. calcium and magnesium salts ✓ Correct
D. only sodium salts
Solution: Ca²⁺ and Mg²⁺ ions react with soap to form an insoluble scum, so little lather forms.
Q4 — Soaps & Detergents · medium · theory
Detergents are preferred over soaps for washing in hard water because detergents:
A. form scum in hard water
B. do not clean
C. dissolve only in oil
D. work well even in hard water ✓ Correct
Solution: Detergents do not form scum with hard-water ions, so they clean effectively in hard water.
Q5 — Soaps & Detergents · hard · theory
The process of making soap by reacting fats/oils with an alkali is called:
A. saponification ✓ Correct
B. neutralisation
C. polymerisation
D. fermentation
Solution: Saponification is the alkaline hydrolysis of fats/oils to produce soap and glycerol.