Class 10 Science - Chapter Our Environment NCERT Solutions | What are the problems caused by the non-

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

Give any two ways in which biodegradable substances would affect the environment.

Which of the following constitute a food-chain?

(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat

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

Why are some substances biodegradable and some non-biodegradable?

Which of the following groups contain only biodegradable items?

(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass

How can you help in reducing the problem of waste disposal? Give any two methods.

What is ozone and how does it affect any ecosystem?

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

What is the role of decomposers in the ecosystem?

Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.

What is a good source of energy?

Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?

What changes can you make in your habits to become more environment-friendly?

What is the difference between a reflex action and walking?

What is the importance of DNA copying in reproduction?

If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?

Why should a magnesium ribbon be cleared before burning in air?

Define the principal focus of a concave mirror.

You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?

Write the balanced equation for the following chemical reactions.

1. Hydrogen  +  Chlorine  →  Hydrogen chloride
2. Barium chloride  +  Aluminium sulphate  →  Barium sulphate  +  Aluminium chloride
3. Sodium  +  Water  →  Sodium hydroxide  +  Hydrogen

How would these advantages differ from the advantages of using a long-term perspective in managing our resources?

A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.

Which of the following property of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer.)

  (a) mass                  (b) speed
  (c) velocity               (d) momentum

Compare and contrast fossil fuels and the Sun as direct sources of energy.

What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?

How would you name the following compounds?

   (i)    CH₃  -- CH₂  -- Br

  (ii)

(iii) 

Explain the importance of fossils in deciding evolutionary relationships.

Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 108 m s–1.

In Activity 13.7, how do we think the displacement of rod AB will be affected if (i) current in rod AB is increased; (ii) a stronger horse-shoe magnet is used; and (iii) length of the rod AB is increased?