SECTION A
What is earthing?
Write the nature of charges on a glass rod and silk cloth when they are rubbed with each other.
13. A little curd is added to warm milk to set curd for the next day. Why? -
A. Write the function of mitochondria.
5 Name the scientist who showed that lightning and spark in the clothes is the same phenomenon. -
If charged plastic straw is brought near another uncharged plastic straw. What will happen?
Freshly collected cow's milk spoils within few hours at room temperature but the milk packet in a sachet
stays good for longer period of time. Why?-
The strips of an electroscope diverge when a charged body is brought in contact with the metal clip. Now
the clip is touched gently by our hand. What will happen to the strip?
T.
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9. Why should we not stand under a tall tree when lightning occurs?
10. What happens if the mitotic division is uncontrolled?
11. Where are chromosomes found in a cell? State their function.
12. Explain why, the disposal of plastic waste is a major problem? Give two reasons. -
12. What is a comet? If Halley's Comet was last seen in 1986, when will it be seen again?
14. Write four important properties of Nylon fibre.
18. What is a lightning conductor? How does it protect the building from lightning?
16. Give any two uses of artificial satellites.
Answer all questions plz . I will mark as brain list and also follow them
Answers
Answer:
1. When a charged object transfers its charges to the earth it is called earthing. Generally, every building is provided with earthing to protect it from electrical shocks due to leakage of electric current.
2. Mitochondria are membrane-bound organelles, but they're membrane-bound with two different membranes. Those membranes function in the purpose of mitochondria, which is essentially to produce energy. That energy is produced by having chemicals within the cell go through pathways, in other words, be converted.
3. In 1752 Benjamin Franklin, an American scientist, showed that lightning and the spark from your clothes are essentially the same phenomena.
4. The charged plastic straw will attract another uncharged plastic straw, when brought near to it because charges of different kind attract each other. The aluminium strips in an electroscope as shown in figure are replaced by plastic strips and a charged body is brought in contact with the metal clip.
5. Freshly collected milk spoils because it is not pastuerized that is heating the milk to certain temperature about 75 degrees and cooling it off. But in the same condition milk packet doesnt spoil because it is pasteurized.
6. If a positively charged object is brought in contact with the metal clip of an electroscope, the negative charge given earlier to the clip will be neutralised and the diverged strips will contact.
7. While passing over a tree or a tall building an opposite charge may be induced causing a lightning to strike the tree or a building and if the charge is large it may cause severe damage and may prove to be fatal. Thus, it is advised to stay away from tall buildings or tree during thunderstorms.
8. In mitosis, the nucleus divides followed by the cytoplasm dividing, resulting in two cells. ... If the cell cycle is not carefully controlled, it can cause a disease called cancer, which causes cell division to happen too fast. A tumor can result from this kind of growth.
9. Chromosomes are found in the nucleus of the cell. They carry genes and help in inheritance or transfer of characters from parents to offspring.
10. Disposal of plastic waste is a major problem because:
1)The articles made of plastic are non-biodegradable. They do not decompose easily. 2)The burning of plastic gives out harmful gases which pollute the air.
11. Comets are cosmic snowballs of frozen gases, rock and dust that orbit the Sun. When frozen, they are the size of a small town. Halley's Comet is arguably the most famous comet. It is a "periodic" comet and returns to Earth's vicinity about every 75 years, making it possible for a human to see it twice in his or her lifetime. The last time it was here was in 1986, and it is projected to return in 2061.
12. The four properties of nylon are
Absorbency
Static Resistance
Heat Resistance
Wrinkle Resistance
13. Lightning rod, metallic rod (usually copper) that protects a structure from lightning damage by intercepting flashes and guiding their currents into the ground. The flow of electricity from a lightning strike is channeled harmlessly around the outside of the building and into the ground.
14. The two uses are
They are used in communication.
They are used in weather forecasting system.
hope it helps