CBSE > Class 09 > Science | CBSE Board | Homework Help

Virtually all soil profiles are composed of a number of distinctive layers, termed horizons, interpretation of which is the key to understanding how the soil has formed.

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An object of mass 40 kg is raised to a height of 5m above the ground .what is its potential energy .

Posted by Jyoti Sharma 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Akanksha Kumari? 7 years, 2 months ago

P.E = mgh = 40× 10× 5 = 2000 J

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A stone is dropped from a height of 10m on an unknown planet .also calculate the time it takes to fall through this height

Posted by Ajay Subray Bhat 7 years, 2 months ago

CBSE > Class 09 > Science

0 answers

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Define hygenic health

Posted by Chiku Kumar 7 years, 2 months ago

CBSE > Class 09 > Science

0 answers

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What are the various energy Transformation that occur when you are burning a cracker

Posted by Isha Saharan 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Simran Das 7 years, 2 months ago

Heat energy -chemical energy-light energy

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A battery lights a bulb. Discribe the energy changes involved in this process

Posted by Isha Saharan 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Anil Singh 7 years, 2 months ago

A chemical energy of battery changes to light energy after that electrical energy converts to light energy and bulb glow

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Why do we clean magnisium ribbon before its burning

Posted by Isha Saharan 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Aditya Kumar Dangi 7 years, 2 months ago

Because magnissium reacts with air and forms magnissium oxide.It forms layer over the ribbon and ressists it from burning.So,it is cleaned before burning.

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Calculate the number of molecules of sulphur present in 16g of solid sulphur

Posted by Isha Saharan 7 years, 2 months ago

CBSE > Class 09 > Science

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What are the differences between broiler and layer and in their management

Posted by Isha Saharan 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Meghna Thapar 6 years, 1 month ago

The diet of broilers is planned with the aim of achieving good growth rate and quality of carcass whereas the diet of layers is aimed to achieve large number and high quality of eggs.

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Which have low boiling point salty water or pure water?

Posted by Diksha Chauhan 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Isha Saharan 7 years, 2 months ago

Salty water have low boiling point

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Difference between xylem and phylum

Posted by Isha Saharan 7 years, 2 months ago

CBSE > Class 09 > Science

2 answers

Raj Dran 7 years, 2 months ago

Xylem tissue transport water & Phloem tissue transport food

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Akanksha Kumari? 7 years, 2 months ago

Did you mean phloem?

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Chemical reactions of H2SO4

Posted by Kanishka Goyal 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Rajdeep Singh 7 years, 2 months ago

hydrogen sulphate

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unit of power

Posted by Harsh Saharan 7 years, 2 months ago

CBSE > Class 09 > Science

2 answers

Vaibhav Singh 7 years, 2 months ago

Watt denoted by w

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Gungun Goyal 7 years, 2 months ago

Watt is the unit of power

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Give one reason why a gas completely fill the vessel in which it is kept

Posted by Ashok Singh 7 years, 2 months ago

CBSE > Class 09 > Science

2 answers

Payal Kaushik 7 years, 2 months ago

A gas completely fill the vessel in which it is kept because it has the highest kinetic energy . The particles of gas are also loosely packed

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Gungun Goyal 7 years, 2 months ago

The force of attraction between the particles of gas is negligible because of this the particles of gas move freely here and there and fill the vessel with gas

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Define 1 Newton 1 joule and 1 watt

Posted by Prabhu Kumar 7 years, 2 months ago

CBSE > Class 09 > Science

2 answers

Meghna Thapar 6 years, 1 month ago

According to Newton’s second law of motion, force acting on a body is the product of mass of the body and its acceleration.

F = m a

The SI unit of force is kg ms−². It is represented by the symbol N.
A force of one Newton produces an acceleration of 1 ms−² in a body of mass 1 kg.Newton = 1 kg × 1 m/s².

One joule of work is said to be done on an object when a force of 1N displaces the object by 1 m along the line of action of force.
When an electrical appliance consumes electrical energy at the rate of 1 joule per second, its power is said to be 1 watt.

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Meghna Thapar 6 years, 1 month ago

According to Newton’s second law of motion, force acting on a body is the product of mass of the body and its acceleration. F = m a
The SI unit of force is kg ms−². It is represented by the symbol N.
A force of one Newton produces an acceleration of 1 ms−² in a body of mass 1 kg.
Newton = 1 kg × 1 m/s².
One joule of work is said to be done on an object when a force of 1N displaces the object by 1 m along the line of action of force.
One watt is the power of an appliance which does work at the rate of 1 joule per second.

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What is green manure?give example of green manure?

Posted by Rahul Gupta 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Khushi Boora 7 years, 2 months ago

Manure formed from young green crop plants ploughed back into the soil. Example dhaincha, guar, lentil and cow pea.

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Who gave the unit theta?

Posted by Khushal Goel 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Akanksha Kumari? 7 years, 2 months ago

It was given by four female students

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Who discovered the law of reflection of light

Posted by Tushar Gupta 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Novil Chauhan 7 years, 2 months ago

Iraqi mathematician Ibn Sahl

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Why is sound wave is called a longitudinal wave?

Posted by Aditya Roy☠️??? 7 years, 2 months ago

CBSE > Class 09 > Science

2 answers

Amey Vikram Singh 7 years, 2 months ago

Sound wave is called as longitudnal wave because when sound wave travel in a medium then medim particle vibrate parallel to its propagation

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Gaurav Seth 7 years, 2 months ago

Longitudinal waves travel in the form of compression and refraction. In the waves the individual particles of the medium move in a direction parallel to the direction of the propagation of the disturbance. The particles do not move from one place to another but they simply oscillate back and forth about their position of rest. This is exactly how a sound wave propagates. Hence, sound waves are longitudinal waves.

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What is the difference between mole and molecules

Posted by Siya Sharma 7 years, 2 months ago

CBSE > Class 09 > Science

2 answers

Amey Vikram Singh 7 years, 2 months ago

Mole is that quantity of any atom or molecule in no having mass equal to its atomic mass or molecular mass in gms Molecule are the group of atoms

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Simran Das 7 years, 2 months ago

Mole is the Avogadro's no. And molecule is the combination of two or more atoms of same kind.

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Difference between xylem $ phloem in short

Posted by Sanjay Sharma 7 years, 2 months ago

CBSE > Class 09 > Science

2 answers

Pratyusha Samantaray 7 years, 2 months ago

Xylem cell have thick walls and many of are dead cells. Xylem transport water and minerals vertically . In phloem material can move in both directions. Phloem transports food. Except for phloem fibres phloem cells are living cells.

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Akanksha Kumari? 7 years, 2 months ago

Xylem helps to transport water and minerals to the plant. It consists of 4 elements: vessels, trachieds, xylem parenchyma and xylem fibre. Phloem helps to transport food materials to the plants. It consists of 4 elements: sieve tube, companion cells , phloem parenchyma and phloem fibre.

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How are simple tissues different from complex???

Posted by Manan Patel 7 years, 2 months ago

CBSE > Class 09 > Science

3 answers

Pratyusha Samantaray 7 years, 2 months ago

Simple permanent tissue are made of one type of cells which look like each other while complex tissues are made of more than one type of cells.

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Gaurav Seth 7 years, 2 months ago

imple tissue	Complex tissue
Simple tissues consist of only one type of cells	These tissues are made up of more than one type of cells.
The cells of simple tissue perform similar function.	The cells of complex tissue may perform different functions.
Example of simple tissues are collenchymas, parenchyma.	Examples of complex tissues are xylem and phloem.

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Abhishek Kumar 7 years, 2 months ago

Simple tissue is made up of only one type of cell whereas complex cell is made up of more than one type of cell.

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Explain conservation of momentum.

Posted by Akanksha Kumari? 7 years, 2 months ago

CBSE > Class 09 > Science

2 answers

Gifty Rajesh 7 years, 2 months ago

STATEMENT: The total momentum before collition is equal to the total momentum after collition.

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Gaurav Seth 7 years, 2 months ago

Conservation of Momentum

When two or more bodies act upon one another,their total momentum remains conserved provided no external force acts on them.

For Ex:When a speeding truck hit a stationary car due to which the car also start moving.

	Truck	Car
Velocity	Decreases	Increases
Momentum	Decreases	Increases

The momentum lost by truck is gained by car.
Momentum can neither be created nor destroyed .
Let us consider a truck and car are moving in same direction but with different speeds.

	Truck	Car
Mass	m₁	m₂
Velocity	u₁	u₂
Initial Momentum	m₁u₁	m₂u₂

Total momentum=m₁u₁ + m₂u₂
_{Suppose the car and truck collide for a short time t , their velocities will change.}

	Truck	Car
Mass	m₁	m₂
Velocity	v₁	v₂
Final Momentum	m₁v₁	m₂v₂

Total Momentum = m₁v₁+ m₂v₂

v₂– u₂

Acceleration of car (a) = ————-

F = m * a

F₁= Force exerted by truck on the car

F₁ = m_{2 *}(v₂– u₂)

———————

v₁ – u₁

Acceleration of truck =————

F₂ = m₁ * (v₁– u₁)

———————

F₁= – F₂

m₂ * (v₂– u₂) – m₁* (v₁– u₁)

——————– = —————–

t t

m₂ (v₂– u₂) = – m₁* (v₁– u₁)

m₂v₂ – m₂u₂ = – m₁ v₁+ m₁ u₁

m₂v₂ + m₁ v₁= m₁ u₁+ m₂u₂

m₁ u₁+ m₂u₂ = m₂v₂ + m₁ v₁

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How is soil formed in short

Posted by Sanjay Sharma 7 years, 2 months ago

CBSE > Class 09 > Science

1 answers

Gaurav Seth 7 years, 2 months ago

Soil is a mixture of rock particles, minerals, decayed organic material, air, and water. The formation of soil happens over a very long period of time and is majorly formed by the weathering of rock. Weathering in turn is the breaking down of huge pieces of rocks into smaller pieces by the action of natural forces, such as water, heat, glaciers, wind and roots of plants, etc.

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What is tincture of iodine??

Posted by Akanksha Kumari? 7 years, 2 months ago

CBSE > Class 09 > Science

2 answers

Gaurav Seth 7 years, 2 months ago

Tincture of iodine or iodine tincture is an antiseptic, it is also called weak iodine solution. Usually 2–7% elemental iodine, along with potassium iodide or sodium iodide, dissolved in a mixture of ethanol and water. Antiseptics are used to kill the animate micro organisms that may be pathogenic or may cause disease.It is used in skin infection.

Since tincture iodine is a mixture of iodine (solid) in alcohol (liquid) it can be treated as solid in liquid solution. It is volatile in nature and can be used as an antiseptic solution.

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Pratyusha Samantaray 7 years, 2 months ago

A solution of iodine in alcohol known as tincture of iodine

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State the property of an element which can be used for its identification.

Posted by Pratyusha Samantaray 7 years, 2 months ago

CBSE > Class 09 > Science