What do you mean by:
$(a)$ Blue revolution?
$(b)$ Yellow revolution?

How is a fumigant different from a pesticide? Name one natural substance which can be used in place of a fumigant.

While selecting a breed of crop,which characteristics of the crop are to be taken into account by the farmers?

Ram tried hard to push the wall of a room. In the process of pushing the wall,he begins to perspire and feels exhausted although the wall does not move. Ram feels that he has done a lot of work and spent a lot of energy. Do you think that Ram was justified in making the statement that he has done a lot of work? Justify your answer and give the conditions under which work is done.

The major groups of activities for improving crop yields can be classified as:

Once Ram's mother Sunita went to her friend's home along with Ram. On visiting there,Ram saw a wet khus-khus screen hung at the door of the room. He asked his mother why they had hung this screen,and his mother answered that it keeps the room cool. Ram was satisfied and smiled.
$(a)$ According to you,what qualities are possessed by Ram?
$(b)$ How does a wet khus-khus screen hung at the door keep the room cool?