List five things you have done over the last one week to —
(a) conserve our natural resources.
(b) increase the pressure on our natural resources.
(a) Five things are following that i have done to conserve our natural resources over the last one week:-
1. I carried paper bags and jute bags while leaving the house for the shopping or for taking vegetables etc.
2. I preferred walking or bicycle to cover short distances instead of going on scooty or automobile appliances.
3. I switched off my rooms or house lights, fans, television which was unnecessarily on.
4. I used pencils for the rough work so that paper can be used again and again.
5. I stopped the tap while brushing the teeth or stopped taking shower and i filled bucket to save water for bathing.
(b) For increasing the pressure on our natural resources, the list of five things which i have done over the last one week are following:-
1. I played video games for the whole day.
2. I forgot to switch off the lights of my bedroom while leaving the room.
3. I threw plastic that is non- biodegradable on the roads.
4. I made paper boats during the rain and play with them.
5. I also forgot to switch off the charger point and left my phone on charging for the whole night which is the wastage of electricity or this can also damage our mobile phones.
Find out about the traditional systems of water harvesting/management in your region.
Suggest some approaches towards the conservation of forests.
We saw in this chapter that there are four main stakeholders when it comes to forests and wildlife. Which among these should have the authority to decide the management of forest produce? Why do you think so?
Find out the source of water in your region/locality. Is water from this source available to all people living in that area?
How can you as an individual contribute or make a difference to the management of (a) forests and wildlife, (b) water resources and (c) coal and petroleum?
Why should we conserve forests and wildlife?
Compare the above system with the probable systems in hilly/mountainous areas or plains or plateau regions.
Why do you think that there should be equitable distribution of resources? What forces would be working against an equitable distribution of our resources?
What changes can you make in your habits to become more environment-friendly?
What can you as an individual do to reduce your consumption of the various natural resources?
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 are trophic levels? Give an example of a food chain and state the different trophic levels in it.
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?
You are given kerosene, turpentine and water. In which of these does the light travel fastest? Use the information given in Table 10.3.
Material medium |
Refractive index |
Material medium |
Refractive index |
Air | 1.0003 | Canada Balsam |
1.53 |
Ice | 1.31 | ||
Water | 1.33 | Rock salt | 1.54 |
Alcohol | 1.36 | ||
Kerosene | 1.44 | Carbon disulphide |
1.63 |
Fused quartz |
1.46 | ||
Turpentine oil |
1.47 | Ruby | 1.71 |
Benzene | 1.50 | Sapphire | 1.77 |
Crown glass |
1.52 | Diamond | 2.42 |
How could the Modern Periodic Table remove various anomalies of Mendeléev’s Periodic Table?
Explain the following.
(a) Why is the tungsten used almost exclusively for filament of electric lamps?
(b) Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
(c) Why is the series arrangement not used for domestic circuits?
(d) How does the resistance of a wire vary with its area of cross-section?
(e) Why are copper and aluminium wires usually employed for electricity transmission?
How can you help in reducing the problem of waste disposal? Give any two methods.
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R′, then the ratio R/R′ is –
(a) 1/25 (b) 1/5 (c) 5 (d) 25
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?
Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Find out, from Table 10.3, the medium having highest optical density. Also find the medium with lowest optical density.
Material medium |
Refractive index |
Material medium |
Refractive index |
Air | 1.0003 | Canada Balsam |
1.53 |
Ice | 1.31 | ||
Water | 1.33 | Rock salt | 1.54 |
Alcohol | 1.36 | ||
Kerosene | 1.44 | Carbon disulphide |
1.63 |
Fused quartz |
1.46 | ||
Turpentine oil |
1.47 | Ruby | 1.71 |
Benzene | 1.50 | Sapphire | 1.77 |
Crown glass |
1.52 | Diamond | 2.42 |
Table 10.3 Absolute refractive index of some material media
How is the sex of the child determined in human beings?