The changes brought by biotic and abiotic factors in food grains that are not stored properly include:

Once Ram's mother Sunita went to her friend's home along with Ram. On visiting there,Ram saw a wet khus-khus screen hung at the door of the room. He asked his mother why they had hung this screen,and his mother answered that it keeps the room cool. Ram was satisfied and smiled.
$(a)$ According to you,what qualities are possessed by Ram?
$(b)$ How does a wet khus-khus screen hung at the door keep the room cool?

Sahil's grandfather had a prostate problem. The doctor advised him to go in for an ultrasound. Sahil accompanied his grandfather to a diagnostic centre. His grandfather went through the process and was given a photograph.
$(a)$ What is the principle of ultrasound? What waves are used for this purpose?
$(b)$ Name four other areas in which the ultrasound is used as a diagnostic tool.
$(c)$ What value did Sahil imbibe about ultrasound?

What do you mean by:
$(a)$ Blue revolution?
$(b)$ Yellow revolution?

In India,about $45 \%$ of the cultivated area is unirrigated,and scarce rainfall often causes crop failure,leading to drought-like conditions. This situation motivated villagers to use rainwater harvesting and watershed management.
$(i)$ What is meant by irrigation?
$(ii)$ List two different kinds of irrigation systems which can be adopted to supply water to agricultural land.
$(iii)$ What values does Rajan possess which helped villagers overcome their problem?

Dalton was the first scientist to use symbols for elements. Chemical symbols act as a vocabulary of chemical language. Chemical symbols are used to describe chemical changes with clarity and precision. Chemical symbols help in identifying specific elements. Chemical symbols also represent an atom of a particular element. Chemical symbols also signify the atomic mass of an element.
$(a)$ How do symbols help in identifying specific elements?
$(b)$ How do we use symbols in daily life for our convenience?
$(c)$ What values do you find in using symbols?