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NCERT Class 10 Science Carbon and its Compounds: In-text questions (page 76) Solutions
AI-written, checked on 23 Oct 2026
Solutions written by Shishya, checked — not the board's official answers
Step-by-step working for every question of In-text questions (page 76) in NCERT's Class 10 Science book, chapter “Carbon and its Compounds”, written by Shishya. Each question is in our own short words; open the NCERT chapter for the exact wording and figures.
How these were checked: the solutions were drafted with AI and then read and corrected on 23 Oct 2026. Every numerical final answer is recomputed from the question's own numbers by a calculator check that runs before each release; proofs and explanations were read, not machine-checked. The NCERT textbook is the authority — if something here disagrees with it, follow the book.
Tap “why?” under a step to see the textbook rule it uses — from Shishya's fixed list of NCERT Class 9-10 rules, not written by AI for this page. A step without one has no rule from the list yet.
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In-text (page 76) Q1
Can you check whether water is hard by using a detergent?
- Detergents are synthetic surfactants that do not form insoluble salts with calcium or magnesium ions.
- When detergent is added to water, it creates a rich lather regardless of the water's hardness.
- Since lather forms in both soft and hard water, the presence or absence of lather cannot indicate hardness.
- Therefore, detergents are not suitable for testing water hardness, unlike soaps which form scum in hard water.
Answer: No, you cannot check whether water is hard by using a detergent because it forms lather in both hard and soft water.
In-text (page 76) Q2
Why is agitation (beating, scrubbing, a washing machine) needed to get clothes clean after adding soap?
- Soap molecules have a hydrophilic head that attaches to water and a hydrophobic tail that attaches to grease.
- When soap touches a greasy stain, the hydrophobic tails penetrate the grease while the heads remain in the water.
- This action breaks the grease into tiny droplets called micelles, which are suspended in the water.
- Agitation provides the mechanical energy needed to break the grease into these small micelles.
- It also helps the micelles detach from the fabric and stay suspended in the water instead of re-attaching.
- Without agitation, the soap cannot effectively surround and lift the grease off the clothes.
Answer: Agitation is needed to break grease into micelles and keep them suspended in water so they wash away.
Other exercises in this chapter
- In-text questions (page 61) — 2 questions
- In-text questions (page 68) — 5 questions
- In-text questions (page 72) — 2 questions
- In-text questions (page 74) — 2 questions
- End-of-chapter exercises — 15 questions
← Carbon and its Compounds: notes, practice and all exercises
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