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

Biogeochemical cycles are the cycles that make possible the transfer of energy and matter among the various components of the biosphere, leading to a balance between them.

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Rutherford model.

Posted by Prahlad Puri 5 years, 8 months ago

CBSE > Class 09 > Science

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Meghna Thapar 5 years, 7 months ago

Rutherford's Atomic Model:

Based on the results of the α-particle scattering experiments, Rutherford put forth his atomic model. An atom contains a positively charged centre called the nucleus of the atom. Almost all the mass of the atom is concentrated in the nucleus. The electrons of the atom revolve around the nucleus in fixed, circular orbits. The size of the nucleus is many times smaller than the size of the atom. The nucleus of an atom is 10,000 times smaller than the atom.

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Please send me all formula of physics chapter 1st CBSE

Posted by Gaurav Thakur 5 years, 8 months ago

CBSE > Class 09 > Science

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What is the length of auditory canal

Posted by Ayush Singh 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Gaurav Thakur 5 years, 8 months ago

. The adult human ear canal extends from the pinna to the eardrum and is about 2.5 centimetres (1 in) in length and 0.7 centimetres (0.3 in) in diameter.

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Biology notes

Posted by Sweety Porwal 5 years, 8 months ago

CBSE > Class 09 > Science

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When an object hanging with the hook of a spring balance is immersed in a liquid, state the factor due to which the reading of spring balance dacrease. Define the factor

Posted by Sonu Sharma 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Ayush Singh 5 years, 8 months ago

It is decreased because of buoyant force of the liquid Buoyant force is an upword force exerted by the fluid or liquid on the object when it is immersed into the fluid or liquid

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In which part the tuberculosis disease found in humans

Posted by Aram Hasan 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Sonu Sharma 5 years, 8 months ago

In Lungs

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Bromine atom is available in the form of two isotopes.79/35Br and 81/35Br are 49.7% and 50.3% respectively. Calculate the average atomic mass of Bromine

Posted by Sonu Sharma 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 5 years, 8 months ago

Average atomic mass of bromine = [79 × 49.7%] + [81 × 50.3%]

={tex} 79 × \frac{49.7}{100} + 81 × \frac{50.3}{100}{/tex}

= 79 × 0.497 + 81 × 0.503

= 39.263 + 40.743

= 80.006 a.m.u

Average atomic mass of bromine = 80.006 a.m.u

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Why rest and motion are called relative terms?

Posted by Aman Kumar 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 5 years, 8 months ago

Rest and motion are the relative terms because they depend on the observer’s frame of reference.
If an observer is at rest in his or her own frame of reference, but he may be moving in other observer's frame of reference. So if two different observers are not at rest with respect to each other, then they too get different results when they observe the motion or rest of a body.

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Compare an electon ,proton ,and neutron in respect of charge

Posted by Sonu Sharma 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Meet Saab 5 years, 8 months ago

An electron have negative charge, that Proton have positive charge and the Newton have not any charge thank you for my answer Think so it will help to u

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Write any three features that all Chordates possess

Posted by Sonu Sharma 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 5 years, 8 months ago

All chordates possess the following features :
(i) have a notochord
(ii) have a dorsal nerve cord
(iii) are triploblastic
(iv) have paired gill pouches
(v) are coelomate.

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What is atomicity of ammonia

Posted by Prem Prakash Kashyap 5 years, 8 months ago

CBSE > Class 09 > Science

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Yogita Ingle 5 years, 8 months ago

The atomicity of ammonia is NH₃:

Ammonia is a compound of nitrogen and hydrogen with the formula NH₃. It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers.

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Truck starts from rest with constant acceleration.It travels a.distance of 200m in 10sec . Find its acceleration

Posted by Sonu Sharma 5 years, 8 months ago

CBSE > Class 09 > Science

2 answers

Aman Kumar 5 years, 8 months ago

u=0 s=200 m t=10 sec a=? s=(u*t)+(1/2*a*t*t) =200m=0+(a/2*10*10) =200m=100a/2 =200m=50a =a=200/50 =a=4 m/(s*s)

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Amrapali Kulkarni 5 years, 8 months ago

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Name the scientists who gave avogadro number

Posted by Kishan Kishan Pal Shakya 5 years, 8 months ago

CBSE > Class 09 > Science

2 answers

Aman Kumar 5 years, 8 months ago

Lorenzo Romano Amedeo Carlo Avogadro ( Amedeo Avogadro )

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David Talukdar 5 years, 8 months ago

Avogadro only

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What is double fertilization?

Posted by Aditya Kumar 5 years, 8 months ago

CBSE > Class 09 > Science

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Why we should classify organisms in different groups?

Posted by Aditya Kumar 5 years, 8 months ago

CBSE > Class 09 > Science

3 answers

Mortal Combat 5 years, 8 months ago

we can classify the organism in different groups by there structure .

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Sonu Sharma 5 years, 8 months ago

To make our study easy and simple about the organism

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Yogita Ingle 5 years, 8 months ago

It is necessary to classify organisms because:

Classification allows us to understand diversity better.
It helps in the identification of living organisms as well as in understanding the diversity of living organisms.
Classification helps us to learn about different kinds of plants and animals, their features, similarities and differences.
It enables us to understand how complex organisms evolve from simpler organisms.
To understand and study the features, similarities and differences between different living organisms, they are grouped under different categories.
Classification is a tool which helps us to deal with a great diversity of living forms.
It is essential to understand the inter-relationships among the different groups of organisms.
Classification forms a base for the development of other biological sciences.

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A train starting from a railway station and moving with uniform accelerate and attains a speed of 40 km/h in 10 min .find its acceleration.??

Posted by Suraj Bhatt 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 5 years, 8 months ago

Here we have,

Initial velocity, u = 0,

Final velocity, v = 40km/h = 11.11m/s

Time (t) = 10 minute = 60x10=600s

Acceleration (a) =?

We know that V = u + at
⇒ 40 km/h = 0 + a (10)m

⇒ 11.11 m/s=a 600sec

⇒ a = 11.11/600 = 0.0185 m/s

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What is gymnosperm

Posted by Pindaa Aale Yaar 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Kritika Dhiman 5 years, 8 months ago

Gymnosperms are phanerogams. Seeds are not enclosed within fruits in these plants. Do not produce flowers. Seeds are naked because ovules are not enclosed by an ovary wall and they remain exposed before and after fertilisation. Eg : Cycus, Juniperus

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what are milich animals

Posted by Hawa Singh 5 years, 8 months ago

CBSE > Class 09 > Science

2 answers

Meghna Sanghvi 5 years, 8 months ago

The animal which give us milk

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Shruti Tyagi 5 years, 8 months ago

Milch animals are the animals which give us milk

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Galnank kya hai

Posted by Rahul Kumar Saket 5 years, 8 months ago

CBSE > Class 09 > Science

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How immune system fight against any microbes?

Posted by Shaili Shree 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Nakshathra S 5 years, 8 months ago

Immune system is formed of WBC cells that produce antibodies against microbes in order to neutralize it.these specialised cells go into action each time when the infected microbes enter the body they also manage to get rid of infection before it assumes major proportion.any vaccine or entry of microbes inside the body act as antigen which create primary immune response . The antigen stimulate the WBC cells that produce antibodies , these antibodies neutralize the effect of antigen and stimulate memory cells to act against future infection. Hope it might be helpful !!!

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How many of you want to become a doctor?

Posted by Shaili Shree 5 years, 8 months ago

CBSE > Class 09 > Science

2 answers

Karan Bungla 5 years, 8 months ago

Nope

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David Talukdar 5 years, 8 months ago

Nope

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Will you separate a mixture containing kerosene and petroleum (differentiate in their boiling point) is more than 25 degree Celsius which are miscible with other

Posted by Samar Kumar 5 years, 8 months ago

CBSE > Class 09 > Science

2 answers

Yashraj Chandel 5 years, 8 months ago

Yes by sublimation. We can do it

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Lakshay Yadav 5 years, 8 months ago

Sublimation

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In water is gravitation force is pressent

Posted by Lokendra Nain 5 years, 8 months ago

CBSE > Class 09 > Science

5 answers

Karan Bungla 5 years, 8 months ago

No there is no gravitational force on water

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Yashraj Chandel 5 years, 8 months ago

Yes there is a force

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David Talukdar 5 years, 8 months ago

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Tanisha Mukherjee 5 years, 8 months ago

Put any object in water gravity can pull the object down through the water only if an equal volume of water is allowed to go up aganist the force of gravity

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Tanisha Mukherjee 5 years, 8 months ago

Yes gravitational force is present in water because if we

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In water is gravitational force is present

Posted by Lokendra Nain 5 years, 8 months ago

CBSE > Class 09 > Science

2 answers

Ritikesh Kumar 5 years, 8 months ago

There Is a gravitational Force because The Special water in mass

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Lokendra Nain 5 years, 8 months ago

l don't e

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Difference between oviparous and viviporous

Posted by Ritikesh Kumar 5 years, 8 months ago

CBSE > Class 09 > Science

3 answers

Aman Kumar 5 years, 8 months ago

Oviparous organisms lay eggs as a result of reproduction.Ex-Birds,fishes,etc.They are pisces,amphibians,reptiles or aves. Viviparous organisms give birth to young ones instead of laying egg as a result of reproduction.Ex-Humans,elephants,etc.They are mammals.

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Sheju Thakur 5 years, 8 months ago

Oviparous have hard shell covering while other are without shells.

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Mohana Mukherjee 5 years, 8 months ago

Oviparous lay eggs.. Viviporous give birth to young ones Eg . Birds, etc. Eg. Human,etc.

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What is the difference between nucles and neucloid? (3 points)

Posted by Tanu Agrahari 5 years, 8 months ago

CBSE > Class 09 > Science