When Ashok visited his village,he observed that villagers were suffering from malnutrition. To curb malnutrition in the village,he suggested they select five or six fish species in a pond. This increased the fish yield from the pond. The villagers were surprised to see the results and asked him to help with the other two ponds in the village.
$(i)$ What name is given to this intensive fish farming?
$(ii)$ Write the basis on which the different fish species are selected.
$(iii)$ Ashok's initiative is worth praising. Give two reasons.

During class,Ravi's teacher was teaching about Thomson's model of an atom,stating that an atom is electrically neutral,i.e.,it contains equal positive and negative charges,and that an atom consists of a sphere of positive charge in which electrons are embedded like plums in a pudding. Ravi wondered how his teacher related Thomson's model of an atom to a plum pudding,and he imagined that just as dry fruits are embedded in a Christmas pudding,electrons are embedded in a sphere of positive charge.
$(a)$ According to you,what kind of qualities does Ravi possess?
$(b)$ What are the limitations of Thomson's model?

Give two examples of milch animals.

Match the column $A$ with the column $B$:

Column $A$	Column $B$
$(a)$ Catla	$(i)$ Bottom feeders
$(b)$ Rohu	$(ii)$ Surface feeders
$(c)$ Mrigal	$(iii)$ Middle-zone feeders
$(d)$ Fish farming	$(iv)$ Culture fishery

Which of the following are Indian cattle?
$(i)$ $Bos$ $indicus$
$(ii)$ $Bos$ $domestica$
$(iii)$ $Bos$ $bubalis$
$(iv)$ $Bos$ $vulgaris$

Fertilizers have short-term benefits whereas manures have long-term benefits. Do you agree with this statement? Give three reasons in support of your answer.