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

Rayon is described as a regenerated fibre because the cellulose, obtained from soft woods or from the short fibres (linters) that adhere to cottonseeds, is converted to a liquid compound, squeezed through tiny holes in a device called a spinnerette, and then converted back to cellulose in the form of fibre.

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How does acid ran effect

Posted by Sumit Kanerkar 5 years, 7 months ago

CBSE > Class 08 > Science

3 answers

Simran Brar 5 years, 7 months ago

1.Acid Rain can damage the crops. 2.It also corrodes the building structures like :Effiel Tower,Taj mahal.

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Mehak Monga 5 years, 7 months ago

When harmful gases like sulphur dioxide and nitrogen dioxide emitted from exhaust pipes of vehicles, factories pawer plant etc react with moisture present in air.They form mitric and sulphur acids.These acids when drop down on earth along with rain called acid rain Affect of a acid rain 1] Skin irrigation 2] It change the fertility of soil and destroy the plants 3] It couses corrosion to building and bridges 4] Due to acid rain soil become too acidic

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Meghna Thapar 5 years, 7 months ago

Acid rain affects plants, pH of the soil, trees, buildings and even statues can be transformed by the precipitation.Acid rain corrodes the marble of the monument. The phenomenon is also called “Marble cancer”.

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A solution is made of 5 ml of alcohol in 75 ml of water find the concentration of the solution in terms of volume percent

Posted by Prateek Jindal 5 years, 7 months ago

CBSE > Class 08 > Science

0 answers

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_______ build up in clouds

Posted by Aswin Prajit 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Raghav Bhutani 5 years, 7 months ago

Charges

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Dash Build up in clouds

Posted by Aswin Prajit 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Palak Gupta 5 years, 7 months ago

Charges

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Mention two application of electroplating

Posted by Prashant Prashant Prajapati 5 years, 7 months ago

CBSE > Class 08 > Science

3 answers

Mehak Monga 5 years, 7 months ago

1] Charmium plating is done on different parts of cars,buses and motor cycle to give then shiny appearance 2] A fine layer of gold is deposited on silver or naments and they are called gold ploted ornament 3] Iron used in construction a building is coated with a layer of zinc.This protect iron from carrosion and rusting

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Gajendra Singh 5 years, 7 months ago

1.It is used in big industry for plating unrust metal on rusting metal.ex nickel on iron. 2.It can be seen in our daily life like cycle,pan and cocker

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Yogita Ingle 5 years, 7 months ago

Chromium plating is done on various objects like car parts, wheel rims, bath taps, etc.
Plating of silver or gold is done on less expensive metals by jewelers.
Iron parts in bridges and automobiles are plated with zinc.
Tin cans for storing food are made by electroplating tin onto iron.

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Define respiration

Posted by Garima Mawari 5 years, 7 months ago

CBSE > Class 08 > Science

3 answers

Utsaw Sagar 5 years, 7 months ago

Taking of oxygen and releasing carbon dioxide is called respiration

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Gajendra Singh 5 years, 7 months ago

It is a process which is usally done by all living being in this the taking of one gas and taking out of another gas is to be done.It has to type in it 1.aerobice and 2. Anaerobic respiration

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Yogita Ingle 5 years, 7 months ago

Respiration is a process where the body uses the oxygen to break down glucose and release energy, so that the cells in the body can use it. Carbon dioxide and water are produced during respiration.

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Who Invented the rabbis vacine?

Posted by Sujith Kumar Vaithilingam 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Simran Brar 5 years, 7 months ago

Louis Pasteur.

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Yogita Ingle 5 years, 7 months ago

Louis Pasteur successfully tests his rabies vaccine on a human subject.

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Write three harmful effect of burning fuel

Posted by Pavleen Bagga 5 years, 7 months ago

CBSE > Class 08 > Science

4 answers

Sakshi Singh 5 years, 7 months ago

Pollution,global warming,green house effect

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Gajendra Singh 5 years, 7 months ago

1.green house effect ., pollution,global warming and result heavy flood in costal region.

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Yogita Ingle 5 years, 7 months ago

Carbon fuels such as wood, coal, petroleum release unburnt carbon particles in the environment. These particles are very dangerous pollutants and cause respiratory diseases for example asthma.
When fuels are incompletely burnt, they release carbon monoxide gas into the atmosphere. This gas is very dangerous as it is poisonous in nature. If we burn coal in a closed room, then the person sleeping in that room will be killed by the action of carbon monoxide.
The combustion of fossil fuels also releases a large amount of carbon dioxide into the atmosphere. Carbon dioxide is a greenhouse gas which is responsible for global warming. Global warming is a rise in the overall temperature of earth’s surface. This leads to melting of polar caps and rise in the sea level and further results in flooding of coastal regions.
Burning of coal and diesel releases sulphur dioxide gas. This gas is extremely corrosive and suffocating in nature. Petrol gives off oxides of nitrogen. The oxides of sulfur and nitrogen get dissolved in rainwater and form acids. This is known as acid rain. This water is very harmful to plants, animals, and various monuments.

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Sujith Kumar Vaithilingam 5 years, 7 months ago

It will consequnces the global warming, And then the green house effect, After the cilmatic change.

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Story of lightning

Posted by Seema Meher 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Kaustubh Mani 5 years, 7 months ago

when the sky light or start thundring the old er peoe think that that is a gods interprinces

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Explain Lightning story

Posted by Seema Meher 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Yogita Ingle 5 years, 7 months ago

Lightning is observed as a bright streak of light during a thunderstorm. Lightning is always accompanied by the sound of thunder. The transfer of charge from clouds to the earth or from cloud to cloud is called lightning. In simple words; lightning is an electric spark which happens on a grand scale in the sky.

Mechanism of Lightning

During a thunderstorm, the air currents move upward and water droplets move downward. These movements take at very fast pace and it results in separation of charges in the clouds.
The positive charges accumulate at the upper edges of the clouds and the negative charges accumulate at the lower edges of the clouds. Scientists are yet to understand the exact reason for this.
At the same time, the ground becomes positively charged.

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How to make human ear by hand

Posted by Ruchit Sanadya 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Kaustubh Mani 5 years, 7 months ago

by half circle

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Ranjana Sharma 5 years, 7 months ago

by hand

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List down all the properties of metal and non metal

Posted by Dev Mashruwala 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Yogita Ingle 5 years, 7 months ago

Some of the physical properties of metals are listed below.

Shiny (lustrous) in nature
Metal is a good conductor of electricity and heat
Density and melting point is high
Mouldable (Malleable)
Ductile
At room temperature, it is in solid form except for mercury
Opaque

Some of the physical properties of non-metals are listed below.

Poor conductors of electricity and heat
Non-Ductile metals
Brittle solids
Maybe solids, liquids or gases at room temperature
These are not sonorous
Transparent

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What is producer gas

Posted by Garena Boss Gaming Boss King 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Palak Gupta 5 years, 7 months ago

It is a low grade fuel gas consisting largely of carbon monoxide and nitrogen which is formed through air and steam.

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What is polymer? With example.

Posted by Ayush Sharma 5 years, 7 months ago

CBSE > Class 08 > Science

3 answers

Dev Mashruwala 5 years, 7 months ago

A polemer is a very big molecul from buy combication large number of molucles called polymer

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Yogita Ingle 5 years, 7 months ago

The term polymer id derived from two greek words POLY meaning many and MER meaning units. Therefore polymer refers to combination of repeating units. Cotton is a natural polymer known as cellulose which is composed of large number of glucose units. Other examples of natural polymers includes silk, wool, cellulose, DNA and proteins. Some of the synthetic polymers are nylon, Teflon polyester, polyethylene etc..

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Shalini Singh 5 years, 7 months ago

Many such small units combine to form a large single unit called a polymer. Polymer examples are cotton

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Why it is dangerous to burn polymers??

Posted by Pavleen Bagga 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Sujith Kumar Vaithilingam 5 years, 7 months ago

The burning of polymer is dangerous. Because it wil produce the carbon monoxide.

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Solenoid

Posted by Pawan Kumar 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Meghna Thapar 5 years, 7 months ago

Solenoid is a long coil containing a large number of close turns of insulated copper wire. The magnetic field produced by passing the current through the coil. Magnetic field produced by the solenoid is similar to the magnetic field produced by the bar magnet. The magnetic field lines in the solenoid are parallel.

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What is elecscope

Posted by Chotu Kumar 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Anshuman Anshu 5 years, 7 months ago

It is a device used to check whether the object is charged

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Shalini Singh 5 years, 7 months ago

What is chapter

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What is a lightening conductor?

Posted by Pavni Wadhwa 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Pavleen Bagga 5 years, 7 months ago

a metal rod or wire fixed to an exposed part of a building or other tall structure to divert lightning harmlessly into the ground.

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what happens when a electrolyte such as copper sulphate is dissolved in water

Posted by Sadhna Gupta 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Pavleen Bagga 5 years, 7 months ago

when a compound dissolves in water, it dissociates to form ions. where the s stands for solid, the l for liquid, and the aq for an aqueous solution in water. The reaction between anhydrous copper sulphur and water is used as a test for water. The white solid turns blue in the presence of water

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What is coal ?

Posted by Hirday Vij 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Yuvraj Singh 5 years, 7 months ago

COAL IS FOSSIL FUEL WHICH IS A NATURAL SUBSTANCE WHICH IS GOING TO EXTINCT

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What is coal gas

Posted by Piyush Thapliyal 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Pavleen Bagga 5 years, 7 months ago

A mixture of gases obtained by the destructive distillation of coal and formerly used for lighting and heating.

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Meghna Thapar 5 years, 7 months ago

Coal gas is a gaseous fuel which is obtained by strong heating of coal in the absence of air during the processing of coal to get coke. When coal gas burns, it produces a good amount of light. So, in the past it has been used for lighting purposes.

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Who discovered the vitamin

Posted by Bhagya Ramesh 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Suhani Singh 5 years, 7 months ago

Casimir Funk

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Pavleen Bagga 5 years, 7 months ago

Casimir Funk

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In which part of a female's body does the fertilization takes place?

Posted by Harasmita Debata 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Pavleen Bagga 5 years, 7 months ago

Oviduct

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Jayant The Mass 5 years, 7 months ago

Oviduct

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Explain circumstances leading to acid rain. How does acid rain affect us?

Posted by Aryan Kumar 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Yogita Ingle 5 years, 7 months ago

Some pollutants like sulphur dioxide and nitrogen dioxide react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid. The acid drops down with rain, making the rain acidic. This is called acid rain. Acid rain affects us in many ways.
(i) Acid rain corrodes the marble of the monument.
(ii) Acid rain damages building and sculptural materials.
(iii) Acid rain damages fresh water also.
(iv) Acid rain also damages our crops and also makes it poisonous.
(v) Acid rain damages the leaves of plants.

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Name one bitumen

Posted by Disha Rahol 5 years, 7 months ago

CBSE > Class 08 > Science