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Gurleen Kaur 6 years, 4 months ago

Petroleum is formed from the living organisms when these organisms died they settle at the bottom of the sea for millions of years in the absence of air and under high pressure. These get converted into petroleum.

Yogita Ingle 6 years, 4 months ago

It was formed by the decomposition of the remains of tiny plants and animals buried under the sea millions of year ago.It is believed that millions of years ago,the tiny plants and animals which lived in sea,died.Their dead bodies sank to the bottom of sea and were soon covered with mud and sand.Due to high pressure,heat,action of bacteria,and in the absence of air,the dead remains of tiny plants and animals were slowly converted into petroleum.The petroleum thus formed got trapped between two layers of impervious rocks,forming oil deposit.

ANSWER

What are difference between single cell and multicellular organisms

Posted by Arpit Sir 6 years, 4 months ago

CBSE > Class 08 > Science

2 answers

Sia ? 6 years, 4 months ago

Unicellular Organisms	Multicellular Organisms
Only one parent is required for reproduction.	Two parents are required for reproduction.
It is a fast process of reproduction.	Slower than unicellular organisms.
No specialized cells are required for reproduction.	Specialized cells are required for reproduction.

Yogita Ingle 6 years, 4 months ago

<th>Unicellular Organisms</th> <th>Multicellular Organisms</th>

The body of the unicellular organism is composed of a single cell.	The body of the multicellular organism is composed of numerous cells.
Irregular in shape.	Have a definite shape.
Simple body organization.	Complex body organization.
A single cell is responsible to carry the life processes.	Different cells are specialized to perform different functions.
The total cell body is exposed to the environment.	Only the outer cells are exposed to the environment.
Division of labour is at the organelle level.	Division of labour is at cellular, tissue, organs and organ system level.
Includes both eukaryotes and prokaryotes.	Includes only eukaryotes.
A lifespan of a unicellular organism is usually short.	These multicellular organisms have a longer lifespan.
Injury to the cell leads to the death of the organism.	Injury to a cell does not cause the cell to die in a multicellular organism.
Reproduce by asexual reproduction.	Reproduce by sexual reproduction.

ANSWER

What is non biodegradable

Posted by Sagar Gautam 6 years, 4 months ago

CBSE > Class 08 > Science

3 answers

Gurleen Kaur 6 years, 4 months ago

The substances that can not degrade or decompose by microorganisms easily is termed as non biodegradable

Tayab Jainapur 6 years, 4 months ago

The substance which cannot decompose called non biodegradable

Ayesha Khatua 6 years, 4 months ago

The substance that cannot easily available to take action by micro organism or not decompose easily is known as non biodegradable substance.

ANSWER

What is biodegradable

Posted by Sagar Gautam 6 years, 4 months ago

CBSE > Class 08 > Science

3 answers

Gurleen Kaur 6 years, 4 months ago

The substances that can degrade or decompose easily is called as biodegradable

Tayab Jainapur 6 years, 4 months ago

The substance which can be easily decompose called biodegradable

Ayesha Khatua 6 years, 4 months ago

The substance that can be easily available to take action by the microorganism and that can be easily decompose is known as biodegradable.substance

ANSWER

Why does pitutary galnds called master glands?

Posted by Dhruv Choudhary 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Sia ? 6 years, 4 months ago

Pitutary gland is called the master gland because it produces hormones that control other glands and many body functions including growth.

ANSWER

Parasites

Posted by Rajkumar Sharma 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Shivani Bisht 6 years, 4 months ago

A parasite is an organism that lives in another organism, called the host, and often harms it. It depends on its host for survival. Without a host, a parasite cannot live, grow and multiply. For this reason, it rarely kills the host, but it can spread diseases, and some of these can be fatal.

ANSWER

What is black gold

Posted by Inba Kumar 6 years, 4 months ago

CBSE > Class 08 > Science

9 answers

Sagar Gautam 6 years, 4 months ago

Black gold is a term applied to oil or petroleum which is black when it comes out of the ground and is worth a great deal and money.

Ujwala Jogalekar 6 years, 4 months ago

Petroleum is called as black gold because of its commercial use and importhance. Petroleum has many constitiuents such as bitumen,LPG,paraffin wax,diesel etc. These are used in many things to manufacture.If we do not refine it is called as crude oil

🖤 🖤 6 years, 4 months ago

Petroleum is known as black gold as it is used in so many things. Examples: lubricating oil, diesel, petrol, paraffin wax, bitumen, LPG, CNG e.t.c.

P Vaishnavi 6 years, 4 months ago

Black gold is another word for petroleum

Gurleen Kaur 6 years, 4 months ago

Petroleum is known as black gold because of its commercial importance

Naman Rathore 6 years, 4 months ago

Petroleum

Shivani Bisht 6 years, 4 months ago

Petrol is known as black gold

Ayesha Khatua 6 years, 4 months ago

Both coal and petroleum are known as Black gold because they are black in colour and they are used in many industries.

Vinod Swami 6 years, 4 months ago

Black gold means crude oil or petroleum

ANSWER

How deforestation leads to reduced rainfall?

Posted by Rohit Yadav 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Yogita Ingle 6 years, 4 months ago

Plants are the main agent to maintain the water cycle in the environment. So cutting of trees reduces the rainfall of that area. If plants will not absorb water from soil they will not evaporate in the environment to form clouds. If clouds will not be formed then no rain-fall takes place. In this way deforestation reduces rainfall.

ANSWER

equation of sulphur and concentrated nitric acid

Posted by Ravi Yadav 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Shivani Bisht 6 years, 4 months ago

NHO3 nitric acid

ANSWER

Highly reactive metal

Posted by Anu Radha 6 years, 4 months ago

CBSE > Class 08 > Science

6 answers

Sia ? 6 years, 4 months ago

francium

Bhavna Sharma 6 years, 4 months ago

sodium

Kezia Deborah Arul 6 years, 4 months ago

Sodium and pottasium are highly reactive they start burning if they are exposed to air or water

Tushar Agri 6 years, 4 months ago

Sodium

Vinod Swami 6 years, 4 months ago

Phosphratet

Chandan Sahoo 6 years, 4 months ago

Pottasium

ANSWER

What is a secularism

Posted by Prashu Tomar 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Sia ? 6 years, 4 months ago

The Indian Constitution contains Fundamental Rights. These rights are very important because they protect us against State power as well as against the tyranny of the majority. The Indian Constitution allows individuals the freedom to live by their religious beliefs and practices as they interpret these. Thus, our Constitution gives religious freedom to all and to maintain it India adopted a strategy of separating the power of religion and the power of the State. Secularism is, in fact, the separation of religion from the State

ANSWER

What is human reprodyctive system and it picture

Posted by Vikas Kumar 6 years, 4 months ago

CBSE > Class 08 > Science

0 answers

ANSWER

What do u mean by destructive distillation

Posted by 🖤 🖤 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Gaurav Seth 6 years, 4 months ago

(a) The strong heating of coal in the absence of air is called destructive distillation of coal.

(b) The various products obtained by destructive distillation of coal are: coal gas, coal tar and coke.

1. Coal Gas:

Coal gas is a gaseous fuel which is obtained by the strong heating of coal in the absence of air during the processing of coal to get coke. Coal gas is mainly a mixture of methane and hydrogen, with some carbon monoxide. All the gases present in coal gas can burn to produce heat, due to which coal gas is an excellent fuel (having high calorific value). Coal gas is used as a fuel in industries. These days, however, coal gas is used as a source of heat rather than light.

2. Coal Tar:

Coal tar is a thick, black liquid having an unpleasant smell which is obtained by heating coal in the absence of air. Coal tar is not a single compound. Coal tar is a mixture of about 200 carbon compounds (or organic compounds). The products of coal tar are used to make synthetic fibres, drugs (medicines), plastics, synthetic dyes, perfumes, paints, varnishes, pesticides, photographic materials, roofing materials and explosives, etc. Coal tar has been traditionally used for metalling the roads.

3. Coke:

Coke is a tough and porous black solid substance Coke is prepared by heating coal in the absence of air. Coke is an almost pure form of carbon. Coke is mainly used as a reducing agent in the extraction of metals (like iron, zinc etc.) Coke is used in the manufacture of steel. Coke is also used as a fuel.

ANSWER

An object at rest starts moving. It covers a distance of 2m in one second. It covers a further distance of 5m in two second in the same direction. What is its average velocity and acceleration

Posted by Sanjive Prema 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Gaurav Seth 6 years, 4 months ago

As we know,
AVERAGE VELOCITY=DISPLACEMENT/TOTAL TIME
HERE, DISPLACEMENT IS 7M BECAUSE THE BODY IS TRAVELLING IN THE SAME DIRECTION AND TOTAL TIME IS 3 SEC.
SO, AVERAGE VELOCITY IS 7/3 M/S
NOW, ACCELERATION=FINAL VELOCITY-INITIAL VELOCITY/TIME
AS WE KNOW SPEED=DISTANCE/TIME
BUT HERE MOTION IS IN STRAIGHT LINE
THEREFORE VELOCITY=DISTANCE/TIME
=5/2=FINAL VELOCITY
INITIAL VELOCITY=0

SO, ACCELERATION=(5/2-0)/2
AND THIS IS EQUAL TO 5/4 M/S

ANSWER

What is explosion combustion

Posted by Siddhu Mehta 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Sia ? 6 years, 4 months ago

An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases.
A chemical process in which a substance reacts with oxygen to give off heat and light is called combustion.

ANSWER

Should the handle and bristles of a tooth brush be made of the same material?

Posted by Kunjal Tantwar 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Sia ? 6 years, 4 months ago

Purpose of the handle of a toothbrush is different from the purpose of bristles of the toothbrush. The handle needs to be strong and less flexible. The bristles need to be highly flexible, soft yet durable. Hence, bristles need to be made up of different material than the material of toothbrush handle.

ANSWER

Avoid plastics as far as possible'. Comment on this advice

Posted by Kunjal Tantwar 6 years, 4 months ago

CBSE > Class 08 > Science

2 answers

Sia ? 6 years, 4 months ago

Since plastic takes several years to decompose, it is not environment friendly. It causes environmental pollution. Besides, when the synthetic material is burnt it takes a long time to get completely burnt. In the process it release a lot of poisonous fumes into the atmosphere causing air pollution.

Tushar Agri 6 years, 4 months ago

PLASTIC RELEASE TOXIC GASSES ON BURNING AND IT ISN'T A BIODEGRADABLE SUBSTANCE ????

ANSWER

Why plastic card colour available in all possible shapes and size

Posted by Rohith M,S 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Meghna Thapar 5 years, 6 months ago

Plastic articles are available in all shapes and sizes because plastic is considered to be a different material as it becomes soft on heating and becomes hard when cooled to lower temperatures. In thermosoftening plastics, the forces between the polymer chains are weak, so they can easily be remoulded into new shapes. This makes it possible to recycle this type of plastic.

ANSWER

An electric heater draws a current of 10 A from a 220v supply. What is the cost of using the heater for 5 hours everyday for 30 days. If the cost of 1 unit is ₹5.20 ?

Posted by Sunita Singh 6 years, 4 months ago

CBSE > Class 08 > Science

0 answers

ANSWER

Defination of flame

Posted by Kirit Patel 6 years, 4 months ago

CBSE > Class 08 > Science

2 answers

Sia ? 6 years, 4 months ago

Flame is a region where gases burn during combustion. Only those substances which vaporise on burning produce flame.

Mahima Kumari 6 years, 4 months ago

Flame is the surface area of burning of any substnace

ANSWER

Synthetic fiber are also called

Posted by Aatish Mavadiya 6 years, 4 months ago

CBSE > Class 08 > Science

6 answers

🖤 🖤 6 years, 4 months ago

Artificial and man made fibre

Khushi Mishra 6 years, 4 months ago

Man made fiber

Divyansh Sharma. 6 years, 4 months ago

Man made fibre

Satyandra Chauhan 6 years, 4 months ago

Artificial or man-made fibre

Ayesha Khatua 6 years, 4 months ago

Artificial fibere and man made fibre also.

Pratik Borle 6 years, 4 months ago

Artificial fiber

ANSWER

Harmful affect of deforestation

Posted by Clash With Himanshu Raj Singhaniya 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Gaurav Seth 6 years, 4 months ago

Global warming: Due to deforestation there is an increase in quantity of carbon dioxide, thereby, increasing the temperature of earth. This is known as global warming. Moreover, it causes harmful effects of skin burning, melting of polar ice caps, increase of seawater level, floods thereby submerging the coastal areas.
Drought: Increase in temperature disturbs water cycle. Therefore it causes less rainfall. thus, this condition of less rainfall causes drought i.e. condition when there is no water for crop as well as drinking
Flood: Trees increases water holding capacity of soil. Moreover, it helps to increase ground water level. Because of deforestation, water cannot be hold for in the ground and so flow of water from the ground surface reduces. Thereby, lowering ground water level. This also increases level of water in the river. If river fails to hold the increase in waterlevel it brings flood.
Soil erosion and desertification: Roots of trees holds the top layer of the soil . Because of deforestation top layer of the soil is removed by water or wind. This is known as soil erosion. This causes change in nutrient content, texture, which gradually converts land into desert
Loss of biodiversity: Forest provides shelter to various plants and animals . By cutting plants humans are disturbing their habitat. Due to which life of such plants and animals are in threat.

ANSWER

Please explain me nitrogen cycle.

Posted by Rekhram Deshmukh 6 years, 4 months ago

CBSE > Class 08 > Science

0 answers

ANSWER

What is fossil fuels??

Posted by Khushi Mishra 6 years, 4 months ago

CBSE > Class 08 > Science

2 answers

🖤 🖤 6 years, 4 months ago

Fossil fuels are fuels that are formed from the remains of dead living organisms. It takes million of years to produce.

Rekhram Deshmukh 6 years, 4 months ago

Fossil fuels are formed from the dead remains of living organism. It takes million of years to produce.

ANSWER

Pls tell me this answer because I am needing..... How is coke formed??

Posted by Anushka ?? Singh 6 years, 4 months ago

CBSE > Class 08 > Science

2 answers

Legend Gaming 6 years, 4 months ago

When large trees and animals dies and their body goes deep into in earth, after million of years, due to great heat and pressure the body converted into coal .This process is known as carbonisation.

🖤 🖤 6 years, 4 months ago

Coke is formed by fractional distillation of coal Contains 90% carbon

3Thank You

ANSWER

What is aquaculture

Posted by Nandlal Dhaker 6 years, 4 months ago

CBSE > Class 08 > Science

1 answers

Sia ? 6 years, 4 months ago

Aquaculture is the farming of fish, crustaceans, molluscs, aquatic plants, algae, and other organisms.

ANSWER

What are weeds ? How we control them ?

Posted by Sahil Yadav 6 years, 4 months ago

CBSE > Class 08 > Science

2 answers

Deborshi Mukherjee 6 years, 4 months ago

We can control them by traditional methods using khurpi or sickle or by using weedicides like rahvant said above 2;4-d

Khushi Panchi 6 years, 4 months ago

Weeds are unwanted plants which grow along crops and compete with them for food shelter and sunlight.....we can control them by using a chemical named 2;4-d