SECTION-B
Answers the following questions in limit of 40 to 50 words:
17. What are weeds? How can we control them?
(2
18. What are antibiotic? What precautions must be taken while taking
antibiotics?
19. Explain the difference between thermoplastic and thermosetting plastics.
20. Give uses of metals and non-metals.
21. Explain the difference between Inexhaustible natural resources and
exhaustible natural resources.
22. Compare LPG and wood as fuels.
23. Explain how deforestation leads to reduced rainfall
Answers
Answer:
17:Weeds are those plants which are useless. we can control by treating them by using artificial pesticides or by hand picking
Answer:
17. Weeds are unwanted and uncultivated plants that grow with crops and compete with crops for nutrients and can also cause crop toxification. Weeding is removal of weeds and is mostly done before flowering begins in crop plants. It is done using trowel, harrow or weedicides. Trowel is used in manual removal of weeds.
18. Antibiotics should be taken in the right amount and at the right time. A wrong dose of antibiotics makes the drug ineffective. Also, excessive consumption of drugs may kill the useful bacteria present in our body.
19. The primary difference between the two is that Thermoset is a material that strengthens when heated, but cannot be remolded or heated after the initial forming, while thermoplastics can be reheated, remolded, and cooled as necessary without causing any chemical changes.
20. Copper is used for making electrical wires, cooking utensils, etc. Zinc is mainly used as a protective coating for iron. Aluminium is used for making electrical cables, packaging, cooking utensils, etc. Non-metals Hydrogen is used for the synthesis of ammonia and methyl alcohol, in welding torches, etc
21. Examples of exhaustible resources are coal and fossil fuel. When most of these resources are used up, they can't be renewed easily or take a too long time to renew. On the other hand, inexhaustible resources can be defined as the resources that can't be exhausted or used up as they exist in abundant and endless supply.
22. LPG has a more calorific value of about 55,000 KJ/ kg as compared to the wood. Wood has a less calorific value of about 17,000 to 22,000 KJ/kg as compared to the LPG. ... It cannot be transported easily as it will have large vehicles as compared to the LPG fuel. LPG has a low value of ignition temperature.
23. This drop occurs because deforestation reduces the natural recycling of moisture from soils, through vegetation, and into the atmosphere, from where it returns as rainfall. ... They combined this with satellite data on precipitation to determine whether the air's increased exposure to vegetation had an effect on rainfall.
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