Crop Production and Management — Science STD 8 — Question

When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?

Give two examples each for a solid, liquid and gaseous fuel along with some important uses.

How do metals react with dilute acids? Explain with the help of an example.

You must have heard farmers talking about soil fertility. What is it? Mention some methods by which soil fertility can be replenished.

How do shadows help explain Moon phases and eclipses?

Name the hormone which would be released during the following situations.
(i) A frightened person
(ii) Growth of a child to adult
(iii) Development of caterpillar to moth
(iv) Development of tadpole to frog

Our Earth is surrounded by a large amount of air consisting of Nitrogen, Oxygen, Argon, Carbon dioxide, and traces of other gases. Layers of air surrounding the Earth are called the atmosphere.
Q.1. What is atmosphere?
Q.2. What is atmospheric pressure?
Q.3. Is the pressure inside our bodies equal to the atmospheric pressure? Why are we not crushed?

Name all the planets of the Solar System in the order of their increasing distances from the Sun.

A strip of impure copper metal is given to you. Describe briefly, how you will purify it by using the chemical of electric current.