Q36 of 805 Page 180

In the context of conservation of natural resources, explain the terms reduce, recycle and reuse. From among the materials that we use in daily life, identify two materials for each category.

OR


Suggest a few useful ways of utilising waste water.

Reduce means less use of commodities or natural resources. Examples – Electricity, water.

Reuse means use of things again and again instead of throwing it away. Examples – Plastic bags, bottles, paper, envelopes etc.


Recycle means by using specific recycling technology new things can be produced from old ones. Examples – Metals, glass apparatus, plastic materials, papers etc.


OR


Few useful ways of utilizing waste water are:


a. It can be used for irrigation purposes.


b. It can be used for recharging ground water.


c. The waste water obtained from water purifier and other sources can be used for gardening, cleaning vehicles, moping floor etc.


d. Sludge separated from sewage can be used as compost or manure.


e. It can be used as cooling water for power plants and oil refineries.


f. Industries can treat the waste water and then letting into water bodies to stop pollution.


More from this chapter

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34

(a) Draw ray diagrams showing the image formation by a convex lens when an object is placed

(i) at twice the focal length of the lens


(ii) at infinity


(b) The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is 80 cm, at what distance has the candle been placed from the lens? What is the nature of the image and the lens?


OR


Write laws of refraction of light. Explain the same with the help of ray diagram, when a ray of light passes through a rectangular glass slab

 35

How will you infer with the help of an experiment that the same current flows through every part of the circuit containing three resistances in series connected to a battery?

OR


Find out the following in the electric circuit given in the Figure.



(a) Effective resistance of two 8 Ω resistors in combination.


(b) Current flowing through 4 Ω resistor.


(c) Potential difference across 4 Ω resistor.


(d) Power dissipated by 4 Ω resistor.


(e) Difference in ammeter readings, if any.

 1

Which among the following statement(s) is(are) true? Silver chloride on exposure to sunlight for long duration turns grey due to

(i) the formation of silver by decomposition of silver chloride


(ii) sublimation of silver chloride


(iii) decomposition of chlorine gas from silver chloride


(iv) oxidation of silver chloride

 2

Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?