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

22K gold jewellery implies that 22 parts of the jewellery amounts to gold and the balance 2 parts are some other metals. This kind of gold is commonly used in jewellery making. In 22K gold, of the 100 per cent, only 91.67 per cent is pure gold. The other 8.33 per cent comprises metals like silver, zinc, nickel and other alloys. It is this addition of metals that make the texture of gold harder thereby making the jewellery durable.

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Why aluminium foil is used for packaging food stuffs

Posted by Hemshikha Kumari 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Maria Aradan 5 years, 7 months ago

aluminium is highly malleable metal and it is very easy to make Aluminium foil in compared to other metals

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Anu Radha 5 years, 7 months ago

Aluminum foil is used because it is less reactive than other ?

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Why sodium and potassium are stored under kerosene?

Posted by Hemshikha Kumari 5 years, 7 months ago

CBSE > Class 08 > Science

5 answers

Mamta Samant 5 years, 7 months ago

Because tPlease etu St hi hu etu are still. Mmmmmmz

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Kumaresh Mondal 5 years, 7 months ago

Because the are more reactiv

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Dr Shalini Mishra 5 years, 7 months ago

Because they are highly reactive Metals

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Deelip Sharma 5 years, 7 months ago

Because they both are very reactive with o2 and h20

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Aditya Prasad 5 years, 7 months ago

Because they are highly reactive with oxygen

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Why metals are used for making utensils?

Posted by Hemshikha Kumari 5 years, 7 months ago

CBSE > Class 08 > Science

4 answers

Maria Aradan 5 years, 7 months ago

aluminium is a type of metal. Aluminium is used for making utensils because Aluminium is unaffected by food acids it is very light metal

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Kumaresh Mondal 5 years, 7 months ago

Because metal and good conducter of heat

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Kumaresh Mondal 5 years, 7 months ago

Aluminium

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Vinusha Suresh 5 years, 7 months ago

Because they have high ignition temperature

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What is the balanced equation for :Zinc reacts with sulphuric acid :Sulphur burns in the presence of oxygen

Posted by Hemshikha Kumari 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Meghna Thapar 5 years, 7 months ago

The zinc will react with sulphuric acid forming zinc sulphate dissolved in solution and releasing hydrogen gas.
Zn (s) + H2SO4 (aq) ---> ZnSO4 (aq)+ H2 (g)

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What is a Kaleidoscope?

Posted by Amita Sinha 5 years, 7 months ago

CBSE > Class 08 > Science

3 answers

Sakshi Jadhav 5 years, 7 months ago

Kaleidoscope is a device that works on the principal of multiple reflection where three plane mirror inclined at an angle of 60 degree

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Dr Shalini Mishra 5 years, 7 months ago

Use for seeing different patterns It is made up of 3 glass rectangles joined together and we put some piece of broken bangles or tiny things to see patterns Hope this helps you

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Yashvi Raghav 5 years, 7 months ago

It is a device which is used to see different patterns. In this 3 plane mirrors are joint together and form a triangle . When something like peices of bangles kept in it , it forms beautiful patterns. It never repeats any pattern

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Why is it difficult to cut cloth using a pair of scissors with blunt blades

Posted by Hemshikha Kumari 5 years, 7 months ago

CBSE > Class 08 > Science

3 answers

Aditya Prasad 5 years, 7 months ago

Because in blunt blades scissors ;it produces low friction as compare to sharp blabes

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Hemshikha Kumari 5 years, 7 months ago

Thanks ?

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Amita Sinha 5 years, 7 months ago

Because of friction....

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I have to know all the states of India where earthquake are more likely to strike

Posted by Lovepreet Saini 5 years, 7 months ago

CBSE > Class 08 > Science

0 answers

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Prepare a beief speech on global warming

Posted by Rekhram Deshmukh 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Maria Aradan 5 years, 7 months ago

the undue rise in the temperature of Earth's atmosphere due to excessive greenhouse effect produced by increasing amounts of carbon dioxide gas in the atmosphere is called global warming. It has become a major concern for the country's because a slight increase in atmospheric temperature can cause serious consequences to all living beings. many countries have reached an agreement to reduce the emissions of greenhouse gases so as to reduce global warming. The kyoto protocol is such an agreement. An important step to reduce the effects of global warming is to minimise the burning of fossil fuels because it emits greenhouse gases such as carbon dioxide, methane, nitrous oxide, chlorofluorocarbons.stress should be laid on the use of alternative sources of energy like solar and wind energy

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Vinusha Suresh 5 years, 7 months ago

Global warming is the rise in temperature of the atmosphere of the earth . This results, among other things, in the melting of the polar glacier, which leads to a rise in the sea level , extreme weather, expansion of deserts.low lying costal areas may even be permanently submerged under water

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Describe green house effect in your own word

Posted by Rekhram Deshmukh 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Aditya Prasad 5 years, 7 months ago

It is a effect in which a co2 absorb heat of sun falls on it

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Explain various agricultural practises?

Posted by Gorkshnath Karale 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Senthil Kumar 5 years, 7 months ago

Psyichs

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Explain the preparation of soil ? 3 mark

Posted by Sapna Khandelwal 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Meghna Thapar 5 years, 7 months ago

Soil is formed from rocks by the process of weathering. In this process rocks are broken down very slowly by the action of sun’s heat, wind, rain, flowing river water etc. to form tiny particles. These tiny rock particles then mix up with humus to form fertile soil.

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Most liquid that conduct electricity are solution of-

Posted by Raj'S Gamers 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Gurleen Kaur 5 years, 7 months ago

Acids, bases and salts

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What are fossil fuels and why it is called so

Posted by Anita Verma 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Harsh Vardhan Chouhan 5 years, 7 months ago

Coal, petroleum and natural gas is known as fossil fuels

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Asif Jawwad Rahman 5 years, 7 months ago

Rst

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What are the methods to prevent water pollution

Posted by Manish K 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Gurleen Kaur 5 years, 7 months ago

Do not throw garbage in water bodies

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Ayush Sharma 5 years, 7 months ago

Do not flow sewage water.

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What is importance of reprodution

Posted by Amit Kumar 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Arpan Naskar 5 years, 7 months ago

To maintain continuiity of a species and prevent its extinction.

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What is meant by spectrum

Posted by Sweetie G 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Harsh Vardhan Chouhan 5 years, 7 months ago

The term spectrum refers to hold an order, different types of light constuting

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Arpan Naskar 5 years, 7 months ago

Spectrum is the band of 7 colours formed by passing white light through a transparent medium like glass prism.

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Comment upon noble metals and use of non metal and alloy

Posted by Aman Rawat 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Meghna Thapar 5 years, 7 months ago

Uses of metals:

(i) Lead metal is used in making car batteries.

(ii) Zinc is used for galvanizing iron to protect it from rusting.

(iii) Iron, copper and aluminium are used to make utensils.

(iv) Copper and aluminium metals are used to make wires.

(v) Aluminium is used to make aluminium foil for packaging materials.

Uses of non-metals:

(i) Hydrogen is used in the hydrogenation of vegetable oils.

(ii) Carbon is used to make electrodes of electrolytic cells and dry cells.

(iii) Nitrogen is used in the manufacture of ammonia, nitric acid and fertilizers.

(iv) Sulphur is used in making sulphuric acid.

(v) Liquid hydrogen is used as rocket fuel.

An alloy is a homogeneous mixture of two or more metals (or a metal and small amount of non-metals) prepared by mixing the various metals in molten state in required proportions, and then cooling their mixture to the room temperature. Alloys do not corrode easily.

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Define solar system

Posted by Naveen Silivery 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Aditya Thakur 5 years, 7 months ago

Solar system is a group of sun, planet,astoried,comat and meteorite

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Yash Yadav 5 years, 7 months ago

The sun celestial bodies which reslove around sun

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Deffine microorganism

Posted by Ish Datt Chaturvedi 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

? ✌️ 5 years, 7 months ago

Microorganisms are unicellular organisms that are invisible to the naked eye but are visible under microscope

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Anushka Yadav 5 years, 7 months ago

Microorganisms are unicellular organism that can be seen only with microscope

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This may result in brain disorder

Posted by Bhawna Malang 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Jayati Thukral 5 years, 7 months ago

Intake of drugs

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Write short notes on the following Cytumplasm Nucleus of a cell

Posted by Darshan Kumar 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Nayan Chaturvedi 5 years, 7 months ago

Cytoplasm and nucleus are present in nucleus it is **** like structure where nucleus things are present like DNA and etc it is it like of cytoplasm where cytoplasm are seat of cell and these cytoplasm are seat of nucleus

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What function does the cytoplasm do?

Posted by Maimoona Shaukat 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Yogita Ingle 5 years, 7 months ago

One of the major functions of cytoplasm is to enable cells to maintain their turgidity, which enables the cells to hold their shape. Other functions of cytoplasm are as follows:

The jelly-like fluid of the cytoplasm is composed of salt and water and is present within the membrane of the cells and embeds all of the parts of the cells and organelles.
The cytoplasm is home to many activities of the cell as it contains molecules, enzymes that are crucial in the break down of the waste.
The cytoplasm also assists in metabolic activities.
Cytoplasm provides shape to the cell. It fills up the cells thus enabling the organelles to remain in their position. The cells, without cytoplasm, would deflate and substances will not permeate easily from one to the other organelle.
A part of the cytoplasm, the cytosol has no organelles. Rather, the cytosol is enclosed by matrix boundaries that fill up the cell section which does not hold the organelles.

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Nayan Chaturvedi 5 years, 7 months ago

It is a seat of cell where many cell organelle present

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Draw a labelled diagram of the human sperm.What makes the sperm mobile

Posted by Aditya Mhaske 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Meghna Thapar 5 years, 7 months ago

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Whats known as menopause

Posted by Saranya Mohan 5 years, 7 months ago

CBSE > Class 08 > Science

2 answers

Aashish Kumar 5 years, 7 months ago

What is smog

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Yogita Ingle 5 years, 7 months ago

Menopause is the time in a woman's life in which the menstrual cycle ends.

Menopause is a stage of a woman's life characterized by the end of her menstrual cycle, and it marks the end of her child-bearing years. As a result of these biological changes, women often experience a number of different symptoms for a period of time, though they eventually subside. It generally happens in a woman's 40s or 50s, though the average age is 51 in the United States. All women go through this stage of life, but if the symptoms cause extreme discomfort or life disruptions, there are some treatment options available.

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If a ball is rolled in noth directon, then which direction will the force of friction act?

Posted by Master Physicist Mars 5 years, 7 months ago

CBSE > Class 08 > Science

3 answers

Gurleen Kaur 5 years, 7 months ago

South

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Simran Brar 5 years, 7 months ago

in south direction

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Master Physicist Mars 5 years, 7 months ago

I think, north direction will be the direction of the fricton as when the ball ? moves, it apllies force towards ➡South direction (imagine it seeing the act of rolling at the contact point of the ground and the ball). So when the force is towards south direction, the friction of course will be towards the north direction. Please correct me if i am wrong.

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How to form soil

Posted by Badal Paswan 5 years, 7 months ago

CBSE > Class 08 > Science

1 answers

Meghna Thapar 5 years, 7 months ago

Soil is formed by weathering. The process by which huge rocks are broken down into small particles by the action of sun’s heat, wind, rain and flowing river water etc. is called weathering. It is called weathering because the rocks are worn away to form small particles by long exposure to the elements of weather. Weathering of rocks is very very slow process. It takes thousands of years to weather huge rocks into fine particles fit to make soil.

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Iast 10 year paper

Posted by Sanjay Singh 5 years, 7 months ago

CBSE > Class 08 > Science