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

Force: It is a push or pull on an object that produces acceleration in the body on which it acts.
First law of motion: An object remains in a state of rest or of uniform motion in a straight line unless acted upon by an external unbalanced force.
Second law of motion: The rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force.
Third law of motion: To every action, there is an equal and opposite reaction and they act on two different bodies.

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What is mesistem

Posted by Vishal Singh 5 years, 7 months ago

CBSE > Class 09 > Science

2 answers

Yogita Ingle 5 years, 7 months ago

Plant tissues in which cells keep on dividing are called meristematic tissue. Meristematic tissues are present in those parts of plants which keep on growing. Meristematic tissues are classified on the basis of their location. They are of following types:

Apical Meristem: Apical meristem is present on root apex, stem apex, leaf buds and flower buds. They are responsible for growth in length, i.e. primary growth.
Lateral Meristem: Lateral meristem is present along the side of the stem. They are responsible for growth in girth, i.e. secondary growth.
Intercalary Meristem: Intercalary meristem is present at the base of leaf or internodes. They are present on either side of the node.

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Bro . 5 years, 7 months ago

The tissue which is responsible for the growth of plants only in certain specific regions,is known as meristmatic tissue or meristem.

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Why do fall il

Posted by Hadhi Vs 5 years, 7 months ago

CBSE > Class 09 > Science

1 answers

Bro . 5 years, 7 months ago

We fall ill because of three reasons -: 1. Due to some infectious agents,like bacteria,viruses etc. 2. Due to the lack if good nourishment. 3. Due to the lack of good public service.

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Describe Rutherford experiment

Posted by Rohit Raj 5 years, 7 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 5 years, 7 months ago

Rutherford’s Scattering Experiment

·Rutherford selected a gold foil as he wanted a very thin layer.

·In his experiment, fast moving alpha particles were made to fall on a thin gold foil.

·Alpha particles are helium ions with +2 charge and have a considerable amount of energy.

·These particles were studied by means of flashes of light they produced on striking a zinc sulphide screen.

·He expected the alpha particles to pass through the gold foil with little deflections and strike the fluorescent screen.

But the observations he made were quite unexpected.

·He observed that most of the alpha particles passed straight through the gold foil.

·Some were deflected through small angles and some were deflected through large angles.

·Very few appeared to bounce back.

From the experiment he concluded that-

·As most of the alpha particles passed through the gold foil without getting deflected, most of the space inside the atom is empty.

·Very few particles deflected from their path; this indicated that the positive charge of the atom occupies very little space.

·A small fraction of alpha particles bounced back by 180 degrees, this indicated that the entire positive charge and mass of the atom was concentrated in a very small volume within the atom.

·Based on his observations, he formulated his ‘Theory of atom’.

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What is the number of electrons to accommodate in N shell

Posted by Kiran Mishra 5 years, 7 months ago

CBSE > Class 09 > Science

7 answers

Sebin Eapen 5 years, 7 months ago

2n^2=2×4×4=32

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S Vinay Kumar 5 years, 7 months ago

32 orbits

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Shourya Utkarsh 5 years, 7 months ago

2n²=2(4)² =2*16 =32

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Yogita Ingle 5 years, 7 months ago

The maximum number of electrons present in a shell is given by the formula 2n², where ‘n’ is the orbit number or energy level index, 1,2,3,…. Hence the maximum number of electrons in different shells are as follows:

first orbit or K-shell will be = 2 × 1² = 2,

second orbit or L-shell will be = 2 × 2²= 8,

third orbit or M-shell will be = 2 ×3² = 18,

fourth orbit or N-shell will be = 2 × 4²= 32, and so on.

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Yogita Ingle 5 years, 7 months ago

first orbit or K-shell will be = 2 × 12 = 2,

second orbit or L-shell will be = 2 × 22= 8,

third orbit or M-shell will be = 2 ×32 = 18,

fourth orbit or N-shell will be = 2 × 42= 32, and so on.

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Swati Burnwal 5 years, 7 months ago

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Abhidev Chaudhary 5 years, 7 months ago

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Dalton atomic theory successfully explained

Posted by Puneet Maurya 5 years, 7 months ago

CBSE > Class 09 > Science

1 answers

Meghna Thapar 5 years, 7 months ago

The Postulates of Dalton's Atomic Theory:

1. All matter is made up of very tiny particles called atoms.
2. Atoms are indivisible particles, which can neither be created nor destroyed in a chemical reaction.
3. The atoms of a given element are identical in mass and chemical properties.
4. Atoms of different elements have different masses and chemical properties.
5. Atoms combine in the ratio of small whole numbers to form compounds.
6. The relative number and types of atoms are constant in a given compound.

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Sir i have mole concept is not clear

Posted by Yash Khare 5 years, 7 months ago

CBSE > Class 09 > Science

2 answers

Saksham Khanna 5 years, 7 months ago

What doubt do you have?

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Madhav Poddar 5 years, 5 months ago

Nikal sale pehli fursat me nikal

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If a a mass of the object in earth is 10 means what will be the mass of the object in the moon

Posted by Fghhhjn Eghhb 5 years, 7 months ago

CBSE > Class 09 > Science

6 answers

Sebin Eapen 5 years, 7 months ago

Mass is always constant, therefore, 10

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Vinit Kumar Dubey 5 years, 7 months ago

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Shourya Utkarsh 5 years, 7 months ago

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Deepali Yadav 5 years, 7 months ago

10/6

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Yash Khare 5 years, 7 months ago

100000????

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Madhav Poddar 5 years, 7 months ago

The mass of the object will remain same

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What are the advantages of composit fish culture

Posted by Payal Bairagi 5 years, 7 months ago

CBSE > Class 09 > Science

1 answers

Bro . 5 years, 7 months ago

Advantages of composite fish culture -: 1. Due to this culture, food available in all parts of pond is used. 2. Due to this culture the yield of fish increases.

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How kilogram force are related to newton

Posted by Kiran Bhatia 5 years, 7 months ago

CBSE > Class 09 > Science

1 answers

Vinay Aggarwal 5 years, 7 months ago

1kilogram Force=9.807 newtons

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What is the full form of science

Posted by Priyanshu Dixit 5 years, 7 months ago

CBSE > Class 09 > Science

4 answers

Priyanshu Dixit 5 years, 7 months ago

Thanku

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Bro . 5 years, 7 months ago

SCIENCE - Systematic Comprehensive Investigation and Exploration of Natural Causes and Effects.

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Chidvilas Bapana 5 years, 7 months ago

SYSTEMATIC COMPREHENSIVE INVESTIGATON AND EXPLORATION OF NATURAL CAUSES AND EFFECT

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Rohit Joshi 5 years, 7 months ago

“Systematic comprehensive, investigation" and “exploration of natural causes and effect" is the full form of science

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How are the wavelenght and frequency of a sound wave related to its speed?

Posted by Sanchita And Priyam Patel 5 years, 7 months ago

CBSE > Class 09 > Science

4 answers

Dhruv Gautam 5 years, 7 months ago

Speed is the product of wavelength and frequency and speed is directly proportional to the product of wavelength and frequency

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Maahi Kumari 5 years, 7 months ago

Velocity=wavelength/frequency

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Narender Kumar 5 years, 7 months ago

Forms of electromagnetic radiation like radio waves, light waves or infrared (heat) waves make characteristic patterns as they travel through space. Each wave has a certain shape and length. The distance between peaks (high points) is called wavelength.

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Yogita Ingle 5 years, 7 months ago

The relation between frequency and wavelength of sound wave is given as follows:

Velocity = Wavelength × Frequency

, v = λ × ν

This means the speed is equal to the product of wavelength and frequency of the sound wave.

This equation is also called the 'wave equation' and applicable to all types of wave.

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Cotton is solid but it floats on water? Give reason

Posted by Rajeshri Kute 5 years, 7 months ago

CBSE > Class 09 > Science

3 answers

Vinit Kumar Dubey 5 years, 7 months ago

Cotton is solid but still it floats on water as it traps air inside the small air gaps made in it. Due to this the density of the cotton decreases and it becomes less denser than water

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Maahi Kumari 5 years, 7 months ago

Since cotton have pores on its surface due to which it trap air in it and hence its density become less than the water and floats in water surface

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Yogita Ingle 5 years, 7 months ago

Cotton floats on water because:

i. Cotton is a solid which has minute (porous) holes.

ii. The holes trap air inside themselves.

iii. As a result, the overall, density of cotton becomes less than water.

iv. Being lighter than water, cotton floats on water.

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Write the relation between velocity frequency and wavelength of the sound wave

Posted by Narender Kumar 5 years, 7 months ago

CBSE > Class 09 > Science

2 answers

Yogita Ingle 5 years, 7 months ago

Let 'T' of the vibrating body = T
Wave Velocity of the body= v
Frequency = f

Wave velocity= Wavelength/Time taken

v= λ/T

v= λ×1/T

[1/T= f]

v= λ×f

Thus, Wave speed= Wavelength × Frequency

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Maahi Kumari 5 years, 7 months ago

Velocity =wavelength/frequency

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Write application of isotope

Posted by Narender Kumar 5 years, 7 months ago

CBSE > Class 09 > Science

3 answers

Bro . 5 years, 7 months ago

Applications of isotope -: 1. An isotope of uranium is used as a fuel in nuclear reactors. 2.An isotope of cobalt is used in the treatment of cancer. 3.An isotope of iodine is used in the treatment of goitre.

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Maahi Kumari 5 years, 7 months ago

Isotope of iodine- for treatment of goitre

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Narender Kumar 5 years, 7 months ago

Isotope. Of uranium = fuel in a nuclear reactor. Isotope. Of cobalt = treatment. Of cancer. Isotope. Of iodine = treatment. Of Goitre

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I confused Which gun is best Akm --- groza. M416-----aug

Posted by Naveen Goyal 5 years, 7 months ago

CBSE > Class 09 > Science

5 answers

David Talukdar 5 years, 7 months ago

M249 and Groza

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Ajeet Pal Minj 5 years, 7 months ago

GROZA and AUG is best in erangle mode

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Aditya Kumar 5 years, 7 months ago

Akm

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Abhishek Sangale 5 years, 7 months ago

Groza

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Naveen Goyal 5 years, 7 months ago

Thanks buddy

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What factors may be responsible for losses of grains during storage?

Posted by Misty Aneja 5 years, 7 months ago

CBSE > Class 09 > Science

5 answers

Arpit Lokhande 5 years, 7 months ago

Biotic factors like pests, insects, rodents,etc. Abiotic factors like climatic conditions, natural calamities, etc.

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Maahi Kumari 5 years, 7 months ago

Moisture in food grains

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Umesh Ingle 5 years, 7 months ago

Temperature, pests, etc

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Shwetha79 Prakash 5 years, 7 months ago

The factors responsible for loss of grain durin storage are: *Moisture remaining in the graing due to improper drting under sunlight *Not spraying pesticides, fungicides, insecticides etc in the granaries *Attack on grains by rodents and pests in granaries

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Kirti Agarwal 5 years, 7 months ago

Moisture left in them

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A solid weighs 15gm in air and 13gm when completely immersed in liquid of relative density 0.8 .Find Volume of solid Relative density of solid

Posted by Arpit Khanna 4 years, 6 months ago

CBSE > Class 09 > Science

1 answers

God Father 5 years, 7 months ago

Loda lele MC

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What is the science of propelling a ship?

Posted by Partha Das 5 years, 7 months ago

CBSE > Class 09 > Science

1 answers

Maahi Kumari 5 years, 7 months ago

Archimedes principal

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xcience

Posted by Aman Kumar Sharma Aman Kumar Sharma 5 years, 7 months ago

CBSE > Class 09 > Science

0 answers

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A ballon contain 10g hydrogen.if 3.02×10^22 molecules are leaked,how many moles of hydrogen will left inside

Posted by Aditya Kumar 5 years, 7 months ago

CBSE > Class 09 > Science

3 answers

Harshit Agarwal 5 years, 7 months ago

1 mole equals 6.022 ×10^22molecules than 3.011 or 3.02×10^22 molecules will be equal to 0.5 moles

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Aditya Kumar 5 years, 7 months ago

I got but not conform

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God Father 5 years, 7 months ago

Aditya kumar khud toh kuch kar le

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Water is evaporated at the rate of 6.02×10^23 molecules per hour.what time will be taken in complete evaporation of 6g of water

Posted by Aditya Kumar 5 years, 7 months ago

CBSE > Class 09 > Science

0 answers

ANSWER

Diffrenshiate between mass and wheight

Posted by Vansh Yadav 5 years, 7 months ago

CBSE > Class 09 > Science

6 answers

Arpit Lokhande 5 years, 7 months ago

Mass is the matter contained in an object. Weight is gravitational force acting on an object. Mass is constant. Weight changes from place to place. SI unit of mass is kg. SI unit of weight is Newton. Mass is represented by small letter m. Weight is represented by capital W and its formula is W= mg. Mass cannot be zero. Weight can be zero. Mass is scalar quantity. Weight is vector quantity.

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Maahi Kumari 5 years, 7 months ago

1) Mass does not change from place to place but weight changes. 2) Mass can never be 0 but weight can be.

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Atiya Rahman 5 years, 7 months ago

#Mass can never be 0 but weight can be 0. #Mass is the inner content of the object but weight is the force with which any object attract towards earth. #Mass can never be changed but weight can changed place to place. #The SI unit of Mass is kg but the SI unit of weight is Newton.

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Arpit Khanna 5 years, 7 months ago

Mass can never be 0.And weight can be 0

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Pooja Agnihotri 5 years, 7 months ago

Mass- mass is the inner content of an object - it is constant. Weight- is the force by which an object is attratcted towards earth. - it is variable. Hope this answer helped!!

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Aditya Kumar 5 years, 7 months ago

Weight=m×g Weight can be changed on different place but mass remain the same

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What mass of ammonia contain same number of molecules as 5.6g nitrogen

Posted by Aditya Kumar 5 years, 7 months ago

CBSE > Class 09 > Science

0 answers

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What is the chemical formula for aluminium oxide ?

Posted by Subhajit Saha 5 years, 7 months ago

CBSE > Class 09 > Science

5 answers

Narender Kumar 5 years, 7 months ago

Al2O3

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Arpit Lokhande 5 years, 7 months ago

Al2o3

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Maahi Kumari 5 years, 7 months ago

Al2O3

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Atiya Rahman 5 years, 7 months ago

Al2o3

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Jobanpreet Kaur 5 years, 7 months ago

Al2O3

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What are cork tissues? How they formed?

Posted by George Kuruvilla Kothapuzhasseril 5 years, 7 months ago

CBSE > Class 09 > Science

2 answers

Maahi Kumari 5 years, 7 months ago

Tissue which do not have living cell. It contains dead cell which act as a protective layer. It is formed of cellulose.

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Yogita Ingle 5 years, 7 months ago

Cells of cork are dead and compactly arranged without intercellular spaces. They also have a chemical called suberin in their walls that makes them impervious to gases and water thus they provide strong mechanical strength to plants.

Cells of cork are dead at maturity.
These cells are compactly arranged.
Cells do not posses intercellular spaces.
Cells possess a chemical substance ‘suberin’ in their walls.
There are several thick layers.
As plants grow older, a strip of secondary meristem replaces the epidermis of the stem. Cells on the outside are cut off from this layer. This forms the several-layer thick cork or the bark of the tree.

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Derivation of Newton first second third law of motion

Posted by Paras Sharma 5 years, 7 months ago

CBSE > Class 09 > Science

1 answers

Aditya Kumar 5 years, 7 months ago

Newton second law of motion "Change in momentum is equal to force applied" Let a body of mass change its velocity from u to v after a time t Initial momentum(P1)=m×u Final momentum(P2) =m×v Change in momentum=P2-P1 =m×v-m×u=m(v-u) Divide this equation by t Change in momentum÷t=m(v-u)÷t And v-u÷t=A Change in momentum ÷ t=m×a m×a =f Change in momentum by t=force

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What are the methods to express concentration of solution

Posted by Xtheandroidgamerx Hd 5 years, 7 months ago

CBSE > Class 09 > Science