Question

21. There are four materials A, B, C and D. A and D are hard and shiny, but B and C are dull and not very hard. Identify the metals and non-metals from A, B, C and D.
22. One day Reeta went to a jeweller’s shop with her mother. Her mother gave an old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?
23. What is meant by fractional distillation? What is the principle on which it is based?
OR
Why should the fossil fuels be used with care?

24. What do you understand by the term “Constellation”? Name any three constellations.
25. Explain why the school bags with wider shoulder strap hurts less than the thinner one?
OR
List three effects that a force can produce.
26. (a) In which part of the sky can you find Venus if it is visible as an evening star? (b) Name the largest planet of the solar system.
(c) Name two objects other than planets which are members of the solar system.
27. What is red data book?
28. What is the difference between unicellular and multicellular organisms?
29. What is irrigation? Describe two methods of irrigation which conserve water.
30. List four causes and consequences of deforestation. What are the causes of extinction of wildlife?
OR
Explain how soil gets affected by the continuous plantation of crops in a field.

Answer 1

Answer:

Phytoremediation, the use of plants to remove or degrade contamination from soils and surface waters, has been proposed as a cheap, sustainable, effective, and environmentally friendly alternative to conventional remediation technologies.