1. What is the range of vision of a normal human eye ?
2. Draw the structure of the simplest ketone.
3. In a certain study conducted on occurrence of DDT along food chains in an ecosystem, the concentration of DDT in grass was found to be 0.5 ppm (parts per million), in sheep it was 2 ppm and in man it was 10 ppm. Why was the concentration of DDT maximum in case of man ?
4. Why has there been so much concern against the use of CFCs ?
5. Why does the clear sky appear blue ?
6. Why does it take some time to see the objects in a dim room when we enter the room from bright sunlight outside ?
7. (a) What happens to a ray of light when it travels from one medium to another having equal refractive ndices ?
(b) State the cause of refraction of light.
8. How has the use of fossil fuels led to the deterioration of environment ? State any two reasons.
9. (a) State Modern Periodic Law.
(b) Why is position assigned to hydrogen in Periodic Table considered anomalous ?
10. Account for the following :
(a) Elements of group l8 are called zero valent.
(b) Elements in a group of periodic table have similar chemical properties.
With the help of an example explain how involvement of local people can lead to efficient management of forests.
11. In what respect is the human male gamete different from the female gamete ?
12. What will happen when :
(a) A mature Spirogyra filament attains considerable length ? (b) Planaria gets cut into two pieces ?
solution to do inke
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