Unpredictable monsoon,droughts,and low rainfall are adversely affecting Indian agriculture.
$(a)$ Mention any two initiatives that have been adopted to increase the availability of water for agricultural purposes.
$(b)$ State two advantages of making check dams.
$(c)$ Briefly describe the canal and river lift systems of irrigation.

Chemical formula of a compound is a symbolic representation of its composition. We should know the following points to write the chemical formulae of chemical compounds:
$(i)$ Symbols of the combining elements.
$(ii)$ Valency of the combining elements.
In order to know the valency,we must calculate the valence electrons present in the atoms.
The electrons present in the outermost shell or valence shell are called valence electrons. The number of electrons in the atoms of some elements are given below. The elements which have one valency are called monovalent.
$(a)$ What is a chemical formula?
$(b)$ Which main points we must know to write the chemical formula of compounds?
$(c)$ Which values do we find associated with the use of formula for various things in daily life?

Cattle husbandry is done for the following purposes:
$(i)$ Milk production
$(ii)$ Agricultural work
$(iii)$ Meat production
$(iv)$ Egg production

Differentiate between inland fisheries and marine fisheries.

Which one is an oil-yielding plant among the following?

What are the merits and demerits of fish culture?