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Yogita Ingle 5 years ago
Force may bring the following change:
1) Can change the state of an object(rest to motion/ motion to rest):For example, pushing a heavy stone in order to move it.
2) May change the speed of an object if it is already moving.For example,catching a ball hit by a batsman.
3) May change the direction of motion of an object.For example,footballer kicks a moving ball to change its direction.
4) May bring about a change in the shape of an object.For example, blowing air in balloon.
5) May cause some or all of these effects.
Posted by Mamata Mamata 5 years ago
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Meghna Thapar 5 years ago
Weeds can be defined as the unwanted plants that are grown in the field and harm the desired crops. Cyperinus is the most invasive weed found throughout the world. It is the weed of rice field. This is the weed which is commonly found in the temperate regions. A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place". Examples commonly are plants unwanted in human-controlled settings, such as farm fields, gardens, lawns, and parks.
Posted by Dharshna Ks 5 years ago
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Meghna Thapar 5 years ago
A cell is a mass of cytoplasm that is bound externally by a cell membrane. Usually microscopic in size, cells are the smallest structural units of living matter and compose all living things. The cell (from Latin cella, meaning "small room") is the basic structural, functional, and biological unit of all known organisms. A cell is the smallest unit of life. ... Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. A cell consists of a nucleus and cytoplasm and is contained within the cell membrane, which regulates what passes in and out. The nucleus contains chromosomes, which are the cell's genetic material, and a nucleolus, which produces ribosomes.
Posted by Archi Agrawal 5 years ago
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Meghna Thapar 5 years ago
The monomers combine with each other using covalent bonds to form larger molecules known as polymers. In doing so, monomers release water molecules as byproducts. This type of reaction is known as dehydration synthesis, which means “to put together while losing water.”
Polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain or network.
During the polymerization process, some chemical groups may be lost from each monomer.
The distinct piece of each monomer that is incorporated into the polymer is known as a repeat unit or monomer residue.
Posted by Khushi Jaiswal 5 years ago
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Meghna Thapar 5 years ago
1. It enables us to select only healthy seedlings for the plants.
2. The process of transplantation promotes better penetration of roots in the soil.
3. It promotes better development of shoot system of plants.
4. The process of transplantation enables us to plant the seedlings at the right spacing so as to ensure the uniform availability of water, nutrients and sunlight to the plants.
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Yogita Ingle 5 years ago
Cells constitute various components of plants and animals. A cell is the smallest unit of life and is capable of all living functions. Cells are the building blocks of life. This is the reason why cells are referred to as ‘the basic structural and functional unit of life’. All cells vary in their shapes, sizes, and activities they perform. In fact, the shape and size of the cell is related to the specific function it performs.
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Anisha Kashyap -09 5 years ago
Meghna Thapar 5 years ago
There are four major types (or “ranks”) of coal. Rank refers to steps in a slow, natural process called “coalification,” during which buried plant matter changes into an ever denser, drier, more carbon rich, and harder material. The four ranks are:
- Anthracite: The highest rank of coal. It is a hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter.
- Bituminous: Bituminous coal is a middle rank coal between subbituminous and anthracite. Bituminous usually has a high heating (Btu) value and is the most common type of coal used in electricity generation in the United States. Bituminous coal appears shiny and smooth when you first see it, but look closer and you may see it has layers.
- Subbituminous: Subbituminous coal is black in color and dull (not shiny), and has a higher heating value than lignite.
- Lignite: Lignite coal, aka brown coal, is the lowest grade coal with the least concentration of carbon.
Posted by Aishwarya Gupta 5 years ago
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Shristi Singh 5 years ago
Meghna Thapar 5 years ago
The formation of fossil fuels is a very slow process, it takes millions of years. Hence, the amount of resources available for use is limited and is being exhausted by human activities like industrialization, rapid growth, etc. Thus, fossil fuels are exhaustible natural resources. The process of formation of fossil fuels requires millions of years. Dead vegetation and animals that get buried deep inside the earth require high temperature and pressure for the formation of fossil fuels, which cannot be done in the laboratory.
Posted by Aryan Thakare 5 years ago
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Meghna Thapar 5 years ago
ANSWER
1. It should possess high calorific value.
2. It should have proper ignition temperature. The ignition temperature of the fuel should neither be too low nor too high.
3. It should not produce poisonous products during combustion. In other words, it should not cause pollution o combustion.
4. It should have moderate rate of combustion.
5. Combustion should be easily controllable i.e., combustion of fuel should be easy to start or stop as and when required.
6. It should not leave behind much ash on combustion.
7. It should be easily available in plenty.
8. It should have low moisture content.
9. It should be cheap.
10. It should be easy to handle and transport.
Posted by Aryan Thakare 5 years ago
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Kethavath Mounika 5 years ago
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Meghna Thapar 5 years ago
Flame is a region where combustion or burning of a gaseous substance takes place. Only the solid or liquids which form gases when heated burn with a flame. Some of the substances which burn by producing flames are LPG, biogas, candle wax, camphor, magnesium and mustard oil.
Charcoal and coal does not burn by producing a flame.
When fuels burn, the type of flame produced depends on the proportion of oxygen available. When the oxygen supply is insufficient, then the fuels burn incompletely and produce mainly a yellow flame and when the oxygen supply is sufficient, then the fuels burn completely and produce mainly a blue flame.
- Structure of a Flame:
There are three zones or parts of a flame – innermost, middle and outer zone.
- Innermost zone: The innermost zone of a flame is dark or black. It consists of hot, unburnt vapours of the combustible material (candle). It is the least hot part of the flame.
- Middle zone: The middle zone of a flame is yellow. It is bright and luminous. In it the fuel vapours burn partially because there is not enough air so it produces carbon particles which become white hot and emit light. This zone is the major part of a candle flame.
- Outer zone: It is non-luminous zone. It is the outer zone of a flame where complete combustion of the fuel takes place because there is plenty of air around it. It has the highest temperature in the flame.
Posted by Anvesha Agrawal 5 years ago
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Rhea Sharma 4 years, 11 months ago
Yogita Ingle 5 years ago
Disadvantages of Synthetic Fibres
- Synthetic fibers require attention while ironing since they tend to melt away easily.
- Most of these fibres absorb very little. So, they stick to the body while sweating on hot summer days. Thus, making it uncomfortable to wear during such days.
- Synthetic fibers are prone to catch fire very easily.
- These fibres are non-biodegradable.
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Posted by Prapti Das 5 years ago
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Peat: It is the youngest variety of coal which is light brown in colour. It contains minimum carbon content and produces less heat and more smoke on burning. Its calorific value is 10 to 15 kJ/g.
Posted by Riya Yadav 5 years ago
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Meghna Thapar 5 years ago
Artificial silk or art silk is any synthetic fiber which resembles silk, but typically costs less to produce. Frequently, "artificial silk" is just a synonym for rayon. When made out of bamboo viscose it is also sometimes called bamboo silk. The process of making viscose silk starts from an alkaline solution of cellulose. The wood or cotton pulp is treated with caustic soda until a merceriza-tion somewhat similar to the chemical reaction in mercerizing cotton yarn has taken place.
Posted by Shreya Kumbhar 5 years ago
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Meghna Thapar 5 years ago
White phosphorus is highly reactive, and spontaneously ignites at about 30°C in moist air. It is usually stored under water, to prevent exposure to the air. It is also extremely toxic, even in very small quantities. In water, white phosphorus reacts with oxygen within hours or days. In water with low oxygen, white phosphorus may degrade to a highly toxic compound called phosphine, which eventually evaporates to the air and is changed to less harmful chemicals.
Posted by Siva Chidambaram 5 years ago
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Yogita Ingle 5 years ago
A plastic which once set,does not become soft on heating and cannot be moulded a second time,is called thermosetting plastic. Once set in a given shape and solidified,a thermosetting plastic cannot be re-softened or re-moulded. They are known as thermosets.
Example: Backlite and thermoset
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Kritika Vaid 5 years ago
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