Conservation of Plants and Animals — Science STD 8 — Question

A man stands 10 m in front of a large plane mirror, so how far must he walk before he is 5 m away from his image?

Why should the foodstuffs like orange juice, pickles, chutney and curd not be kept in iron or aluminium containers?

A factory was started near a village. Suddenly, villagers started feeling the presence of irritating vapours in the village. Mr. Lalit Jain was school teacher in that village. He noted that the cases of headache, chest pain, cough, dryness of throat and breathing problems are increasing among the villagers. He blamed the emission from the chimney of the factory for such problems. He gave the written complain in behalf of all the villagers.
Read the given passage and answer the following questions.
(i) Explain what could have happened in the village.
(ii) What values are shown by Mr. Lalit Jain ?

How do metals react with dilute acids? Explain with the help of an example.

Draw a labeled diagram of the human male reproductive system.

Discuss the effects of deforestation on the following. Cities (Urban areas).

A wall reflects light and a mirror also reflects light. What difference is there in the way they reflect light?

How do astronauts talk to one another on the surface of moon and why?

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

State any two physical properties for believing that aluminium is a metal.