While making shikanjwi,Savy was aware of which substances to use,added sugar,salt,and water in different amounts,and mixed them thoroughly. She was amazed as it tasted the same throughout.
$(a)$ According to you,what qualities are possessed by Savy?
$(b)$ Why do you think shikanjwi tastes the same throughout?

$(a)$ Give two examples of shellfishes.
$(b)$ Mention the names of four marine fish of high economic value.

Which one is not a source of carbohydrate?

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?

Kavita,the science teacher,was teaching her students about the types of diseases based on duration: acute and chronic diseases. She also discussed their ability to spread in public and their immediate causes.
$(a)$ What are acute and chronic diseases? Give one example of each.
$(b)$ Name the type of diseases which spread by coming in contact with a sick person. Name the different types of organisms which cause diseases.

Give two examples of milch animals.