What is the advantage of green manure?

Gautam visited a fair along with his classmates. There he found that a hawker was selling balloons filled with helium gas. His teacher told the students that the balloons will rise in the sky and then stop after some distance. Gautam questioned his teacher as to why the balloons would stop. He started arguing with his teacher that the balloons would rise indefinitely. His teacher got irritated with him. Just then,Gautam's friend Avdesh took him aside and explained to him that the teacher was correct. The explanation given by Avdesh satisfied Gautam.
$(a)$ Why will the balloon stop after rising to a certain height?
$(b)$ What values are shown by Avdesh and Gautam?

$(i)$ Mr. Ramdin,an educated farmer,convinces his friends to use fertilizers judiciously. Why?
$(ii)$ Which two values of Ramdin impress you?

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.

What are those crops called which are grown in the winter season?

How do biotic and abiotic factors in stored grains lead to poor marketability? How can these factors be controlled?