What do you understand by composite fish culture?

Two friends,Girish and Neeraj,were discussing Newton's third law. They were perplexed about how action and reaction are equal and opposite. They could not think of an experiment by which they could ascertain this fact. Pushkar,who was their friend,told them that he would set up an experiment to prove this to them. By performing an experiment,Pushkar demonstrated the law.
$(a)$ Can you think of an experiment by which you can demonstrate this law?
$(b)$ What values do you think Pushkar has?

How do biotic and abiotic factors in stored grains lead to poor marketability? How can these factors be controlled?

Find out the correct sentence:
$(i)$ Hybridisation means crossing between genetically dissimilar plants.
$(ii)$ Cross between two varieties is called as interspecific hybridisation.
$(iii)$ Introducing genes of desired character into a plant gives genetically modified crop.
$(iv)$ Cross between plants of two species is called as inter-varietal hybridisation.

Fill in the blanks:
$(a)$ Pigeon pea is a good source of . . . . . . .
$(b)$ Berseem is an important . . . . . . crop.
$(c)$ The crops which are grown in the rainy season are called . . . . . . crops.
$(d)$ . . . . . . are rich in vitamins.
$(e)$ . . . . . . crop grows in the winter season.

Write three advantages of crops growing in shorter duration of time compared to those growing in longer duration of time.