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Class 10 | NCERT Solution | Chapter: 13

✅ Q1. Which of the following groups contain only biodegradable items?

🎯 (a) Grass, flowers and leather

✅ Q2. Which of the following constitute a food chain?

🎯 (b) Grass, goat and human

✅ Q3. Which of the following are environment-friendly practices?

🎯 (d) All of the above

✔ Carrying cloth-bags while shopping

✔ Switching off unnecessary lights and fans

✔ Walking to school instead of using vehicles

✅ Q4. What will happen if we kill all the organisms in one trophic level?

🎯 The entire food chain will collapse:

• Organisms at the next trophic level will starve and decrease in number.
• Organisms at the previous level may grow excessively, disturbing the ecosystem balance.

✅ Q5. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

🎯 Yes, the impact will be different at each level because:

• Removing producers eliminates food for all consumers.
• Removing top predators can cause overpopulation of lower levels.
  🎯 No trophic level can be removed without causing damage, as all levels are interconnected.

✅ Q6. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

🎯 Biological magnification refers to the increase in concentration of harmful chemicals (like pesticides) in organisms at higher trophic levels of a food chain.

🎯 Yes, it is higher at the top of the food chain because chemicals accumulate in bodies over time and get concentrated as they move up the chain.

✅ Q7. What are the problems caused by the non-biodegradable wastes that we generate?

🎯 Problems include:

• Pollution of soil, water, and air.
• Harm to wildlife and marine life.
• Blocking of drains and rivers.
• Long-term damage to ecosystems as these materials persist for years.

✅ Q8. If all the waste we generate is biodegradable, will this have no impact on the environment?

🎯 Even biodegradable waste can harm the environment if produced in excess:

• Overloads decomposers.
• Can produce foul smell, methane gas.
• Can contaminate water and reduce soil fertility if unmanaged.

✅ Q9. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

🎯 The ozone layer protects us from harmful UV rays that can cause skin cancer, cataracts, and harm plants and animals.

🎯 Steps to protect ozone:

• Banning of ozone-depleting substances (like CFCs) through agreements like the Montreal Protocol.
• Encouraging use of eco-friendly products and technologies.

Class 10 | NCERT Solution | Chapter: 12

 Here are the answers to the questions from Chapter: Magnetic Effects of Electric Current (Class 10, NCERT, CBSE):

✅ Q1.

Which of the following correctly describes the magnetic field near a long straight wire?

• (d) 🎯 The field consists of concentric circles centred on the wire.

✅ Q2.

At the time of short circuit, the current in the circuit:

• (c) 🎯 increases heavily.

✅ Q3.

State whether the following statements are true or false.

• (a) The field at the centre of a long circular coil carrying current will be parallel straight lines. → ✅ True
• (b) A wire with a green insulation is usually the live wire of an electric supply. → ❌ False (Green is used for earth wire, not live)

✅ Q4.

List two methods of producing magnetic fields:

🎯

• Passing an electric current through a straight conductor.
• Using a permanent magnet.

✅ Q5.

When is the force experienced by a current–carrying conductor placed in a magnetic field largest?

🎯 When the conductor is placed perpendicular to the magnetic field.

✅ Q6.

Imagine you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall to front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?

🎯 Using Fleming’s left-hand rule, the magnetic field is directed vertically downward.

✅ Q7.

State the rules:

• (i) 🎯 Magnetic field around a straight conductor → Right-Hand Thumb Rule: If the thumb of the right hand points in the direction of current, the curled fingers show the direction of magnetic field.
• (ii) 🎯 Force on a current-carrying conductor → Fleming’s Left-Hand Rule: Thumb = force, First finger = field, Second finger = current.
• (iii) 🎯 Current induced in a coil → Fleming’s Right-Hand Rule: Thumb = motion, First finger = field, Second finger = induced current.

✅ Q8.

When does an electric short circuit occur?

🎯 When the live wire and neutral wire come into direct contact, causing a sudden, large current due to very low resistance.

✅ Q9.

What is the function of an earth wire? Why is it necessary to earth metallic appliances?

🎯 The earth wire provides a low-resistance path for current to the ground in case of leakage of current.

🎯 It is necessary to earth metallic appliances to prevent electric shock and protect the user.