Class 10 Science - Chapter Our Environment NCERT Solutions | What will happen if we kill all the orga

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?

What do you mean by a precipitation reaction? Explain by giving examples.

What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?

Can the wing of a butterfly and the wing of a bat be considered homologous organs? Why or why not?

An atom has electronic configuration 2, 8, 7.

   (a)  What is the atomic number of this element?
   (b)  To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses.)
          N(7)      F(9)      P(15)      Ar(18)

How can three resistors of resistances 2 Ω, 3 Ω, and 6 Ω be connected to give a total resistance of (a) 4 Ω, (b) 1 Ω?

An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed.

Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.

(a) What will be the action of gas on

      (i) dry litmus paper?
      (ii) moist litmus paper?

(b) Write a balanced chemical equation for the reaction taking place.

What is hydrogenation? What is its industrial application?

In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?