CBSE > Class 08 > Science | CBSE Board | Homework Help

We will design a circuit to see that thermoplastics are poor conductors of electricity. We need a bulb, some wires, a battery, a piece of metal, and a plastic pipe. Set up the circuit first with the metal and then with the plastic pipe (as shown in the figure).

After you switch on the current, you will observe that the bulb glows in the former case. In the latter case, the bulb does not glow. Hence, a plastic pipe (which is a thermoplastic) is shown to be a poor conductor of electricity.

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ANSWER

Write any two uses of plastic

Posted by Ishita Gohel 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Gaurav Seth 4 years, 11 months ago

(i) Plastics are bad conductors of heat. Thus, they are used in making the handles of cooking vessels, containers for microwave oven and in refrigerators.

(ii) Plastics are bad conductors of electricity and used as covering materials in electrical appliances, wires, cords etc.

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Difference between alloy and metaloid ?

Posted by Nibir Mahanta 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Gaurav Seth 4 years, 11 months ago

Metalloid is an element which show some properties of metals and some properties of non metals. Examples are, Silicon, germenium, etc.

An alloy is a homogenous mixture or metallic solid solution composed of two or more elements. Alloys usually have different properties from those of the component elements. Example, brass, bronze, steel, etc.

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What are the elements of metals ?

Posted by Nibir Mahanta 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Yogita Ingle 4 years, 11 months ago

Metals: Those materials which possess the characteristic of being hard, shiny, malleable, fusible, ductile, etc. are termed as metal. Few examples of metals are iron, gold, silver, aluminium, copper, etc.

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What are weeds and how weeds affect a crop

Posted by Roshi Mahajan 4 years, 11 months ago

CBSE > Class 08 > Science

2 answers

Nibir Mahanta 4 years, 11 months ago

The undesirable plants that grow naturally along with the crop are called weeds.

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Sneha Rawat 4 years, 11 months ago

Weeds are the undesirable plants that grow along with the crop. The compete with the crops for water, sunlight etc and effect the growth of the crops

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ANSWER

Why bronze preferred over copper metal for making statues?

Posted by Aman Singh 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Yogita Ingle 4 years, 11 months ago

As bronze metal is harder and more malleable in nature it is used to make statues.It also has the property of ductility and can easily be shaped into a statue.Therefore,bronze is used for making statues than copper.

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ANSWER

Why iron is not used to make electric cable

Posted by Yashika Tripathi 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Yogita Ingle 4 years, 11 months ago

The reasons for iron is not used in making electrical wires are as follows:

1. Iron is very brittle in nature.

2. It gets corroded when comes in contact with oxygen in nature.

3. The resistivity of iron is large. Iron also has 5 1/2 times more resistance than the same size copper wire, so it will get 5 1/2 times hotter, and have 5 1/2 times more voltage losses, when carrying the same current as the copper wire.

4. Used as wire conductor will cause a lot of power waste, this will reduce the voltage of the power supply system, resulting in electrical appliances do not work .

5. Compared with copper and aluminum, the iron is unstable and easily oxidized. After oxide (rust), its resistance is further increased, and it is easy to cause damage.

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ANSWER

Why are coal , petroleum and natural gas are called fossil fuels..?... Please answer me

Posted by Khushi Chaudhary 4 years, 11 months ago

CBSE > Class 08 > Science

2 answers

Gaurav Seth 4 years, 11 months ago

Fossil fuels were formed from the buried remains of plants and tiny animals that lived hundereds of millions of years ago. Coal, petroleum, natural gas and propane all are formed by same process and hence known as fossil fuels.

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Riya Arora 4 years, 11 months ago

Because they are naturally formed and take a millions of years to form by the process of carbonisation

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ANSWER

Why is India not making methane even if the components are there? Please answer my question.

Posted by 505 Sree Krishna Kottam 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Yashika Tripathi 4 years, 11 months ago

Because it is not possible to make methane

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ANSWER

An iron tablet prescribe by the doctor doesn't look like iron but still it cures iron efficiency . Explain ?

Posted by Renu Gandhi 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

The Ambivert 4 years, 11 months ago

Our body contain iron right? Still we aren't iron man that's why there is a huge difference in both iron

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ANSWER

Why are farmers dependent on rain even they have aa irrigation facilities? They says that Rain water can grow plant helthy.

Posted by Anoop Kumar 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Meghna Thapar 4 years, 11 months ago

Water is essential for all life on the farm. Farmers obtain most of the water for their crops from rain. Rainwater that is not absorbed by the soil and plant roots runs into streams and rivers. Farmers in areas where there is not enough rain for their crops to grow must irrigate their fields. If there are rivers in that particular region then the farmers can construct short canals from the rivers and use that water for irrigation. 4) Farmers should conserve rainwater through building water storage tanks so that every drop of rainwater is conserved for future use.

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ANSWER

What is the main component acrylic

Posted by Aishwarya Gupta 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Yogita Ingle 4 years, 11 months ago

Acrylic is a strong, lightweight and warm synthetic fibre that resembles wool. It is available in a number of colours and is more durable and affordable than natural wool.

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ANSWER

For a force to come into play the two concerned bodies must ? with each other

Posted by Nancy Sharma 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Sneha Rawat 4 years, 11 months ago

Interract with each - other

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ANSWER

Describe an experiment to show that pure water is a poor conductor of electricity?

Posted by 👌Aditya 👌 👌Kumar👌 4 years, 11 months ago

CBSE > Class 08 > Science

2 answers

👌Aditya 👌 👌Kumar👌 4 years, 11 months ago

Thanks

1Thank You

Yogita Ingle 4 years, 11 months ago

Pure water does not conduct electricity, but naturally occurring water (rain water, tap water etc) contain salts (ions) dissolved in it and this makes it a good conductor of electricity

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ANSWER

Write down 200 new word science class 8

Posted by Harshit Mishra 4 years, 11 months ago

CBSE > Class 08 > Science

0 answers

ANSWER

What is pinus

Posted by Mayuresh Pathak 4 years, 11 months ago

CBSE > Class 08 > Science

0 answers

ANSWER

What is Mario

Posted by Omkar Vartak 4 years, 11 months ago

CBSE > Class 08 > Science

0 answers

ANSWER

What is meant by fungi

Posted by Honaji Shelgave 4 years, 11 months ago

CBSE > Class 08 > Science

2 answers

Yogita Ingle 4 years, 11 months ago

Fungi are usually multicellular eukaryotic organisms which cannot make their own food and are dependent on other living organisms for their food requirements.

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Chokkiyan Nanammal 4 years, 11 months ago

Member of Eukaryotic organism includes microorganisms like yeast and molds

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ANSWER

Which fibre is known as artificial silk?

Posted by Hardik Verma 4 years, 11 months ago

CBSE > Class 08 > Science

5 answers

Mayank Dhull 4 years, 11 months ago

Rayon

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Shreyas Patil 4 years, 11 months ago

Rayon is known as artificial silk

0Thank You

Chokkiyan Nanammal 4 years, 11 months ago

Rayon is an artificial silk. Rayon is a fibre was obtained by chemical treatment of wood pulp

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Meghashree S 4 years, 11 months ago

Rayon

0Thank You

Santosh Dwivedi 4 years, 11 months ago

Rayon is known as artificial silk. It was first developed and produced in 1880 as artificial silk due to silk- like appearance and cheap cost of production.

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ANSWER

Locket the National Park on political map

Posted by Yugank Jha 4 years, 11 months ago

CBSE > Class 08 > Science

0 answers

ANSWER

What is nytrogen cycle . Explain

Posted by Saksham Dewan 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Yogita Ingle 4 years, 11 months ago

Nitrogen cycle is all about the movement of nitrogen between various elements on Earth (like air, soil, living organisms etc.) The amount of nitrogen in the atmosphere remains constant.

Atmosphere has approx. 78% nitrogen.
Atmospheric Nitrogen is fixed into the soil
- N₂ fixing microbes convert atm. N₂ into nitrogen compounds like NH₃
Plants utilize nitrogen from soil through their roots
Animals utilize nitrogen, feeding on plants
When Plants & animals die, Nitrogenous wastes are returned to soil
- Decomposers convert some part to nitrogen compounds to be used by plants
- Denitrifying bacteria convert into atm. N₂

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ANSWER

Write the commercial use of microorganisms

Posted by Pratik Sahu 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Khushi Sharma 4 years, 11 months ago

It is used in alcohol , wine ,bread ,making cakes in factories as commercial usesof microorganism

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What is ductility??

Posted by Shreyas Patil 4 years, 11 months ago

CBSE > Class 08 > Science

1 answers

Santosh Dwivedi 4 years, 11 months ago

The property of metal by which it can be drawn into wires is called ductility.

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ANSWER

Pickles are kept in plastic bottles because

Posted by Nikita Deokar 4 years, 11 months ago

CBSE > Class 08 > Science

2 answers

Janhavi Paraye 4 years, 11 months ago

If acids kept in metal container it may be destroyed and form holes in utensil

1Thank You

Gaurav Seth 4 years, 11 months ago

Pickles contain acids (namely citric) Which when stored in Metal containers react with the metal forming a salt,hydrogen gas and thereby spoiling both the content and the container.

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ANSWER

kosika kisa kahata ha

Posted by Sudhan Singh 4 years, 11 months ago

CBSE > Class 08 > Science