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

Lichens are not found in populated area as Delhi is populated area whereas the hills are not much populated so this is the reason behind that lichens do not occur in Delhi whereas they commonly grow in hills

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Anashuman Singh 7 years, 1 month ago

Lichens are perfect indicators of air pollution. Excessive air pollution kills them. Therefore, they grow commonly in hills where air pollution is negligible and not in delhi where the air is filled with pollution.

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Who is thomas edison

Posted by Kartik Makhija 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Yogita Ingle 7 years, 1 month ago

Thomas Alva Edison (1847-1931) held 1,093 U.S. Patents including a stock ticker, a mechanical vote recorder, a battery for an electric car, electrical power, recorded music and motion pictures. Explore his life and work in these lessons, activities, and resources.

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Kartik Makhija 5 years, 11 months ago

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Explain the force by which the earth attract?

Posted by Avi Kapoor 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Anashuman Singh 7 years, 1 month ago

Gravity is the gravitational force between any object and the earth.

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How to ace a science exam ?

Posted by Joyeta Bhadury 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Anashuman Singh 7 years, 1 month ago

Most important things: Equations in chemstry, numericals in physics and diagrams in biology

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Force of750 acting on body of mass 30 kg diapalaces 16 m find the total work done by the body

Posted by Prashant Tiwari 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Diya Tahiliyani 7 years, 1 month ago

work = force × displacement, = 750×16 =12000 Nm work

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Why do meristematic tissues cell lack vacuoles?

Posted by Harshad Solanki 7 years, 1 month ago

CBSE > Class 09 > Science

3 answers

Diya Tahiliyani 7 years, 1 month ago

Main function of meristematic tissue is to divide, but the main function of vacuole is storage,so meristematic tissue lack vacuoles

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Joyeta Bhadury 7 years, 1 month ago

Meristrmaric tissue cells are dynamic in nature as they constantly uave to divide and form new cells. The greater the number of meristematic cells in a plant body, the greater is its chances to grow. Vacuoles in plant cells are usually large . The presence of such a vacuole will force the cell to occupy more space resulting in a total loss of meristemaric cells as they diminish in number. Also, the presence of a vacuole also creates problems in efficient cell division by reducing its dynamity .

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Tarun Kumar 7 years, 1 month ago

Pata nhi

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What is the role of a lysosomes in a cell

Posted by Narendra Sethi 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Gaurav Seth 7 years, 1 month ago

Role/Functions of Lysosomes:

(i) Extracellular digestion. Sometimes lysosome enzymes are released outside the cell to break down extracellular material.

(ii) Digestion of foreign material. Lysosomes also destroy any foreign material such as bacteria.

(iii) Cellular digestion. Lysosomes help in the breakdown and digestion of various substances inside the cell

(iv) Waste disposal - Lysomes acts as suicidal bags and digest any damaged or worn out cells of the cell they are present in.

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Harshad Solanki 7 years, 1 month ago

It helps in digesting the waste of cell

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what is chromatography and its application??

Posted by Sanidhya Patel 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Anashuman Singh 7 years, 1 month ago

Chromatography is that technique which is used to separate those solutes that dissolve in the same solvent. Applications: 1. To sepate different colours from a dye. 2. To extract pigments from natural colours. 3. To separate drugs from blood.

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Sneha Yadav 7 years, 1 month ago

It is a technique to seperate different colors from a dye. It works upon principle that more colour dissolved would rise upward than the color which is dissolved less. Principle - Used to extract different pigments from a dye. Used to analyse drug in the blood.

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Which object is fall down? A ston or a feather

Posted by Fun With Science 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Namratha M Vivek 7 years, 1 month ago

If it is not vaccumed stone falls first as friction will be offered by air to the feather If it is vaccumed then both falls togetherly as gravitation remains ame for all the objects.

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What is mole and its unit

Posted by Md Abbas Hussain Bhole 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Akash Tiwari 7 years, 1 month ago

mole content number of entities as like ions atoms molecules electron neutron Proton acceptor is equal to the number of carbon atoms present by 12 gram of carbon. 1 mole = 6.022 *10 ^ 23 atoms

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Ricky Samuel 7 years, 1 month ago

Mole is a group of two or more no of atoms combined together It is avagadro no of particles ??

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Formula of boron carbonate

Posted by K Shanmukh 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Akash Tiwari 7 years, 1 month ago

B2(co3)3

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Why do we wear cotton cloths in summer?

Posted by Parijat Sinha 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Akash Tiwari 7 years, 1 month ago

We should wear cotton clothes in summer because during summers we tend to sweat a lot and cotton fabric absorbs this sweat and helps the body to cool down. ... Cotton allows better air circulation, which helps in absorbing and removing body moisture caused by sweat.

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Durgesh Kumar Singh 7 years, 1 month ago

It absorbs sweat from our body. We feel comfort.

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Define inertia and types of inertia .

Posted by Disha Jain 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Durgesh Kumar Singh 7 years, 1 month ago

The tendency of any object to resist the change in their shape and size is called inertia. Two types of inertia. 1. Inertia in rest. 2.inertia in motion.??

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Shreeya Gupta 7 years, 1 month ago

the tendency of the body to oppose any change is called the inertia there are three types of inertia first inertia of rest second inertia of motion third inertia of direction

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If the moon attract the earth ,why does the earth not move towards the moon

Posted by A V 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Śâhíľ Singh Øbérôy 7 years, 1 month ago

Moon attracts the earth with same force but due to high mass of earth , earth doesn't move towards the moon

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Durgesh Kumar Singh 7 years, 1 month ago

Moon and earth attract each other by equal force. so, earth don't moves towards the moon.

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why does a desert cooler cool better on a hot day

Posted by Nikhil Goel 7 years, 1 month ago

CBSE > Class 09 > Science

4 answers

Akash Tiwari 7 years, 1 month ago

The cooling in a desert cooler is caused by the evaporation of water. A desert cooler cools better on a hot and dry day because the higher temperature on a hot day increases the rate of evaporation of water and the dryness of air (low humidity of air) also increases the rate of evaporation of water. And due to increased rate of evaporation of water, a desert cooler cools better on a hot and dry day.

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Durgesh Kumar Singh 7 years, 1 month ago

Because of evaporation.

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Account Deleted 7 years, 1 month ago

It is right

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Nikhil Rana 7 years, 1 month ago

Because of evaporation that cause cool effect

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Who discovered proton, neutron and electron

Posted by Arpit Jindal 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Durgesh Kumar Singh 7 years, 1 month ago

Proton-Gold stein. Electron-J.J.Thomson. Neutron-J.Chadwik

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Akanksha Kumari? 7 years, 1 month ago

Proton was discovered by Eugen Goldstein. Neutron was discovered by James Chadwick. Electron was discovered by J.J Thomson.

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A boy weighing 50 kg climbs up a vertical height of 100 m. Calculate the amount of work done by him

Posted by Shivam Gujjar 7 years, 1 month ago

CBSE > Class 09 > Science

4 answers

Sk Kumar 7 years, 1 month ago

50000J

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Durgesh Kumar Singh 7 years, 1 month ago

-49000joules

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Khiladi Bhai 7 years, 1 month ago

Mass=50 H=100 W=? g=-9.8 W=mgh W=50×-9.8×100 W=5×-98×100 W=-490×100 W=-49000 W=49000Joule

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Honisha Bhardwaj 7 years, 1 month ago

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What is the atomicity?find the atomicity of H2So4

Posted by Khiladi Bhai 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Durgesh Kumar Singh 7 years, 1 month ago

Number of atoms in a molecule. 7 atomicity

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Mitanshu Khandal 7 years, 1 month ago

The number of atoms constituting a molecule is known as its atomicity. The atomicity of H 2 s o4 is seven since it contains two atoms of hydrogen one atom of Sulphur and four atoms of oxygen. 2+1+4=7

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What is Gravity????

Posted by Avi Kapoor 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Durgesh Kumar Singh 7 years, 1 month ago

Force by which earth attract anything towards its center

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Khiladi Bhai 7 years, 1 month ago

Gravity is the force which the earth exerts on body towards it .Gravity is the weakest force in the universe

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Example on the cooling caused by evaporation

Posted by Atul Singh 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Durgesh Kumar Singh 7 years, 1 month ago

When we put some acetone on our palm

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Khiladi Bhai 7 years, 1 month ago

When their is sweating on body the body get cooled

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In what way is the Rutherford atomic model different from that of Thomson's atomic model

Posted by Fardeen Khan 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Khushi Choudhury 7 years, 1 month ago

* Thomson atomic model is a watermelon model . *Thomas atomic model tells that electron present in positive sphere.

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Why in pot if we keep water it gets cool ?

Posted by Pranaw Kumar 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Pranaw Kumar 7 years, 1 month ago

Because water goes in the small pores of the pot and it get evaporated and earlier we have studied that evaporation causes cooling

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What do you mean by immune response ?

Posted by Ruchi Kanojia _☺️ 5 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Meghna Thapar 6 years, 1 month ago

When the immune system first sees an infectious microbe, it responds against it and then remembers it specifically. So the next time that particular microbe, or its close relatives enter the body, the immune system responds with even greater vigour. This eliminates the infection even more quickly than the first time around. This is the basis of the principle of immunization.

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Derivation of all 3 equation of motion

Posted by Vinay Gupta 7 years, 1 month ago

CBSE > Class 09 > Science

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Name the scientific names and divisons or phylum: 1. Balanoglossus. 2. Spirogyra. 3. Mustard. 4. Funaria. 5. Fern. 6. Earthworm. ( If don't know , I will tell you.)

Posted by Paras Sharma 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Paras Sharma 7 years, 1 month ago

Scientific names: 1. Balanoglossus. 2. Spirogyra. 3. Brassica. 4. Funaria. 5. Arthyrium filix femina. 6. Pneretima. Divisons: 4. Bryophyta. 5. Pteridophyta. 2. Chorophyta. 3. Magniliophyta. Phylums: 1. Hemichordata. 6. Annelida.

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How are living organism dependent on soil ?Are organism that live in water totally independent of soil as resource

Posted by Adarsh Pandey 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Meghna Thapar 6 years, 1 month ago

Soil Teeming With Life:

Various organisms like plants, animals and micro-organisms are found in soil. Earthworms are also found in the soil. The soil is composed of different types of components like humus, clay, sand and gravel. If we add a handful of soil in water and stir and do not disturb it for sometime, we can observe different layers of soil.

Uses of soil:

It is essential for agriculture. Soil is used for growing food like grains, pulses etc.
Soil is used to grow trees for obtaining wood for building purposes for making as fuel and for making paper.
It is also used to grow cotton plants and mulberry trees.
Soil is also used to make earthenware or pottery.

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What is third law motion

Posted by Shreyaspati Mishra 5 years, 11 months ago

CBSE > Class 09 > Science

4 answers

Màñjèét Sìñgh 7 years, 1 month ago

Action to reaction

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Pranaw Kumar 7 years, 1 month ago

Newton's third law is: For every action, there is an equal and opposite reaction. The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object

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Rahul Kumar 7 years, 1 month ago

Every action has an equal and opposite reaction

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Ayush Mittal 7 years, 1 month ago

Action and reaction are always equal and opposite to one another . They always act on two different bodies

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What is colour of ammonium chloride and sodium chloride

Posted by Avi Kapoor 7 years, 1 month ago

CBSE > Class 09 > Science