1. Why are metals good conductors of electricity?
Ans Metals are good conductors of electricity, because they have free electrons. These free electrons act as charge carriers in the metallic structure allowing electric current to flow through the metal.
2. Which is called brightest stars of our solar system?
3. What is the first stage of nutritional blindness?
Ans: A person cannot see in dim light or night
4. What is the leading cause of blindness?
Ans: Cataract- In this case eye lens became cloudy and vision became hazy.
5. What are the moons of mars?
Ans: Phobos and Deimos.
6. In electrolysis of water, hydrogen is formed at cathode
7. Mention three disadvantages of using coal as a fuel?
Ans: (a) It produce lot of soot, (b) it produce poisonous gas carbon mono oxide on burning in an insufficient supply of air(O2) (c) It also produce oxide of nitrogen and sulphur that pollute air
8. Petrol made from source other than petroleum is called Synthetic petrol.
9. A natural fountain of hot water and stream is called geysers.
10. The process by which carbon content of coal increases is called Carbonisation.
11. Balance these equations:
2 Na + 2H2O -----> 2 NaOH + H2
CH4 + 2 O2 ----> CO2 + 2 H2O
2C + O2 ----> 2 CO
2Cl2 + 2H2O ----> 4 HCl + O2
Mg + H2O ----> MgO + H2 (Balanced already)
2H2 + O2 -----> 2H2O
12. How does deforestation causes flood and drought?
Ans: Deforestation of mountains, slopes and uplands causes water to rush down to the rivers. This causes the rivers to overflow and lower lands get flooded. Example: Deforestation of Himalayas has been causing floods in India, Bangladesh and Pakistan every year.
Forests hold water and deforestation causes water to rush down very fast. Because of this, the uplands get deprived of water, soon after the rains. This leads to droughts in the uplands. Example: Deforestation of Himalayas in India has changed the perennial streams into seasonal streams that run out of water soon after the monsoon.
13. What is shifting cultivation? What impact does it have on forest?
Shifting cultivation is a method of clearing forest for agriculture and moving to another area forest once soil gets exhausted. Shifting cultivation led to large scale destruction of forests and causes loss of primary forest.
14. Biodiesel is made from animal fat and vegetable oil
15. Natural gas is used to produce carbon black. [Reason: Carbon black is a product of natural gas.]
16. Write briefly about Chipko Andolan?
Ans: Chipko Andolan is believed to have started in 1973 in Gopeshwar village in Chamoli district (Uttarakhand) and spread over the Himalayas region. It was started to save the trees. The women of Garhwal district forced the contractor to stop deforestation and leave. Many environmentalists got inspired by this and the movement rapidly spread across the Himalayan region under the leadership of Sunderlal Bahuguna and Chandi Prasad Bhatt.
17. What are exotic species? How they harm biodiversity?
Ans: Exotic species are those species of plants and animals that do not originally belong to a particular place but are introduced in it from some other place. These species often grow by destroying native species of that area as they compete for space and nutrition with the native species. Example: Spotted deer introduced in Andaman and Nicobar Islands is exotic to that place and has proliferated, as it does not have natural predators. It is now damaging the forest plants and crop plants.
18. All the development projects have to get environmental clearance from the government.
19. Non identical twins are also called fraternal twins.
20. The placenta is attached to embryo by the Umbilical Cord.
21. Define these terms:
Foeticide: The act that cause death of foetus is called Foeticide
Cyanobacteria: A kind of bacteria that can obtain their energy through photosynthesis. Cyanobacteria are often called "blue-green algae.
Cyanobacteria get their name from the bluish pigment phycocyanin, which they use to capture light for photosynthesis. They also contain chlorophyll a, the same photosynthetic pigment that plants use.
Taboo: A religious custom or practice that restrict certain practice or behaviour like widow marriage
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