The oil-yielding plant among the following is:

Balwinder was a small farmer. As his field was rain-fed,he could not take the risk of growing specialized crops. He used to mix the seeds of two crops and sow them in the field. Kaku,his son who passed class $IX$,suggested growing two or more crops simultaneously in a definite pattern. Balwinder followed this,and the productivity per unit area increased.
$(i)$ Name the cropping pattern which Balwinder used earlier and the one suggested by Kaku.
$(ii)$ Write two advantages of practicing the pattern suggested by Kaku.
$(iii)$ Write two values displayed by Kaku.

Find out the correct sentence about manure:
$(i)$ Manure contains large quantities of organic matter and small quantities of nutrients.
$(ii)$ It increases the water holding capacity of sandy soil.
$(iii)$ It helps in draining out excess water from clayey soil.
$(iv)$ Its excessive use pollutes the environment because it is made of animal excretory waste.

Find out the wrong statement from the following:

Name the type of nutrient that we get from mustard seeds and linseed.

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?