Light — Science STD 8 — Question

What will you observe when the metal top of an electroscope is touched with:

1. A positively charged object?
2. A negatively charged object?

How do viruses differ from other micro-organisms such as bacteria?

Man, A has a defect of vision due to which he cannot see the nearby objects clearly (though he can see the distant objects clearly). On the other hand, man B has a defect of vision due to which he cannot see the distant object clearly (though he can see the nearby objects clearly). The defect in man A can be corrected by using spectacles containing lenses C whereas the defect in man B can be corrected by using spectacles containing lenses D.

1. Name the defect of vision in man (i) A, and (ii) B.
2. What type of lenses are (i) C, and (ii) D?

Consider the following animal species:
Dodo, Yak, Deer, Black buck, Tiger, Cow, Kashmir stag, Dinosaur, Elephant, Lion tailed macaque, Peacock, Snow leopard
Which of these animals are:

1. Endemic to mountain habitats?
2. Endangered species?
3. Extinct species?

What is a comet? Name the comet which was last seen in 1986 after a period of 76 years.

Describe the sprinkler system of irrigation. State its advantages.

Define asexual reproduction. Name two methods of asexual reproduction in animals. Name two animals which reproduce by these asexual reproduction methods.

What is meant by 'celestial objects'? Name any three celestial objects.

Define adolescence. State some of the change which take place in boys and girls during adolescence.

What will happen if the natural habitat of a wild animal is destroyed?