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

A mole of a defined substance is defined as the mass of that substance containing the same number of fundamental units just like atoms in 12.0 g of 12C. These fundamental units can be atoms, molecules, or formula units based on the substance. It represents the number of chemical elements.One mole of any substance is equal to the Avogadro number whose value is 6.023 x 10²³. It can be used to measure the products in a chemical reaction. The unit is defined denoted by mol.

The number of moles formula is given by
Number of moles = mass of substance / mass of one mole

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Explain law of conersation of mass

Posted by Bad Boy 7 years, 1 month ago

CBSE > Class 09 > Science

4 answers

Zainab Parwez 7 years, 1 month ago

Mass can neither change nor destroy

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Amrut Dani 7 years, 1 month ago

you have any sample question papers

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Amrut Dani 7 years, 1 month ago

Law of conservation of mass states that mass can neither be created nor be destroyed in a chemical reaction

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Om Agrawal 7 years, 1 month ago

Mass cannot be created cannot be destroyed .

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Blue print of science

Posted by Navya Chitturi 5 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Akanksha Maurya 7 years, 1 month ago

In this app see in. Cbse syllabus

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Why some children are unheathy

Posted by Prayag Raj 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Akanksha Maurya 7 years, 1 month ago

Some children are still unhealthy because of their unbalanced diet .The food provided to them does not fill the need of nutrients they need .Also,medical problems is attached to it

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Zainab Parwez 7 years, 1 month ago

Its depends on heridetary

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Why crystallisation is better than evaporation,,?????????

Posted by Praneeth Gidnandi 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 7 years, 1 month ago

Crystallization is a process that separates a pure solid in the form of its crystals from a solution.
Crystallization is better than evaporation because during Evaporation:
1) Some solids decompose or some, like sugar may get charred on heating to dryness.
2) Some impurities may remain dissolved in the solution even after filtration, which on evaporation contaminates the solid.

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Define the joule

Posted by Dimple Mohnani 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Amrut Dani 7 years, 1 month ago

1 J is the amount of work done on an object when a force of 1 N displaces it by 1 m along the line of action of the force

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Difference between Aids and HIV

Posted by Arun Bhatt 7 years, 1 month ago

CBSE > Class 09 > Science

4 answers

Zainab Parwez 7 years, 1 month ago

AIDS stands for acuired immuno deficiency

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Zainab Parwez 7 years, 1 month ago

HIV is a virus which causes aids..here aid is a desease and virus is a host

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Palak ?? 7 years, 1 month ago

HIV causes AIDS,.. HIV is a virus whereas AIDS is a disease....

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Praneeth Gidnandi 7 years, 1 month ago

AIDS--: stands for (acquired immune diffincy virus) .means it is acquired and nor passed to babies??? before birth. HIV--: stands for human immune diffincy virus.

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What is the components of solution

Posted by Himanshu Meena 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Zainab Parwez 7 years, 1 month ago

Solute and solveny

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Nitin Jangra,?✌ 7 years, 1 month ago

1. Solute 2. Solvent

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Sample paper 2018

Posted by Rajeev Kumar 7 years, 1 month ago

CBSE > Class 09 > Science

0 answers

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Difference between mass and inertia

Posted by Jay Joshi 7 years, 1 month ago

CBSE > Class 09 > Science

3 answers

Paridhi Sharma 7 years, 1 month ago

Mass is the measure of inertia Where as Inertia is the tendency of an object to resist change in motion or rest until an external force is applied.

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Sk Kumar 7 years, 1 month ago

Mass is the measure of inertia

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Prakhar Lohbare 5 years, 11 months ago

mass is mass and inertia is inertia

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State reason for the following-1 tape worms do not have digestive tract-2 frog have both skin and lungs for breathing

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Paras Sharma 7 years, 1 month ago

Frogs have both skin and lungs for breathing because as they are amphibians (live both in land and water) so by skin they breathe in inside the water and by lungs they breathe at land.

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Nitin Jangra,?✌ 7 years, 1 month ago

Tape worm live in intestine in which digested food. Is present so tape worm eat food which is already digested so they don't need a digestive system

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List out any four features that all chordates possess

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Ayush Mahla 7 years, 1 month ago

1) They are bilaterally symmetrical 2) They have a notochord 3) They are triploblastic 4) They have a Dorsal nerve chord 5) They have respiratory system like lungs, gills and skin for breathing.

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what is function of notochord

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Nitin Jangra,?✌ 7 years, 1 month ago

notochord is the defining structure of the chordates, and has essential roles in vertebrate development. It serves as a source of midline signals that pattern surrounding tissues and as a major skeletal element of the developing embryo. Genetic and embryological studies over the past decade have informed us about the development and function of the notochord. I

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Paridhi Sharma 7 years, 1 month ago

Notochord is a long supportive string like structure which provides support to the chordates and also seperate gut from the nervous tissue.

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What is inflammation write the symptoms of this in human body

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

0 answers

ANSWER

why whales are not grouped in the fishes while sea horse is a fish

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Pratyusha Samantaray 7 years, 1 month ago

Whales are not grouped in the fishes as they possess mammary gland. Hence ,they are mammal .But sea horse lay eggs and they are categorized as Pisces. Hence they are called fish.

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Write the main features of kingdom fungi

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Paridhi Sharma 7 years, 1 month ago

1. They are eukaryotic. 2. They have cell wall. 3.They are saprophytes i.e. they feed over dead and decaying matter. 4. They can become multicellular at certain stages of life. 5. Their cell wall is made up of complex sugar calle chitin. 6. They can also live in symboitic relationship with blue-green algae which is known as lichens

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Thallophyta bryophyta and pteuidophyta are classified as cryptogamae whereas gymnosperm and angiosperm are classified as phanerogamae why

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Ayush Mahla 7 years, 1 month ago

Thallophyta, Bryophyta and Pteridophyta are called Cryptogamaes because they have hidden reproductive organs called spores instead of seeds for reproduction while Gymnosperms and Angiosperms are called Phanerogamaes because they have seeds for reproduction.

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Is there is no answers for all the sapmle papers????

Posted by Akshita Rohilla 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Akanksha Maurya 7 years, 1 month ago

No 3 rd one contains the answer in science

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Draw and identify different element of xylem and phloem

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Meghna Thapar 6 years, 1 month ago

Complex tissues are made of more than one type of cells. All these cells coordinate to perform a common function. Xylem and phloem are examples of such complex tissues. They are both conducting tissues and constitute a vascular bundle.

Xylem –

Xylem is a vascular and mechanical tissue. It consists of tracheids, vessels, xylem parenchyma and xylem fibres. Except xylem parenchyma, all xylem elements are dead and bounded by thick lignified walls. Tracheids and vessels are tubular structures which transports water and minerals vertically. The parenchyma stores food and helps in the sideways conduction of water. Fibres are mainly supportive in function.

ii. Phloem –

Phloem contains tubes but performs no mechanical function. Phloem is made up of four types of elements: sieve tubes, companion cells, phloem fibres and the phloem parenchyma. Sieve tubes are tubular cells with perforated walls. Phloem is unlike xylem in that materials can move in both directions in it. Phloem transports food from leaves to other parts of the plant. Except for phloem fibres, phloem cells are living cells.

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Name the different compounds of xylem

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Himani Saini 7 years, 1 month ago

Xylem fibres, xylem parenchyma,tracheids, xylem vessels

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What is average atomic mass

Posted by Dheeraj Mehra 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Ayush Mahla 7 years, 1 month ago

Average atomic mass is the sum of two isotopes of an element

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Yashika Gupta 7 years, 1 month ago

No.of protons+no.of neutrons

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Mention some measures to control water pollution

Posted by Mustafa Khan 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Mohita Khare 7 years, 1 month ago

Less use of fertilizers Water should be treated before going in water Use of manure

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What are the differences between animals belonging to the aves group and those in the mammalia group?

Posted by Taha Mateen 7 years, 1 month ago

CBSE > Class 09 > Science

1 answers

Himani Saini 7 years, 1 month ago

Main difference between the animals belonging to Aves and those in the mammalian group is that Aves lay eggs and mammals give birth to young one also Aves are mostly aerial but mammals are terrestrial ial

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Life exis from pre existing cell

Posted by Md V 7 years, 1 month ago

CBSE > Class 09 > Science

0 answers

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Air is cosidered a mixture and not a compound . Explain

Posted by Sonalika P. 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Kunal Gupta 7 years, 1 month ago

Air is considered aa a mixture of gases because it contains many gases such as oxygen carbon dioxide nitrogen etc but not in a fixed proportion. Compounds are formed due to combining of elements in a fixed proportion and air has no fixed proportion so air is a mixture not a compound

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Anshi Chhajed 7 years, 1 month ago

Mixture. Because it has many gases in it such as oxygen ,carbon dioxide, nitrogen. Not sure

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We give a force of earth and earth pull towards by gravitaion and according 3rd law of motion every action has it equal and opposite reaction explain???

Posted by Vicky Nagle 7 years, 1 month ago

CBSE > Class 09 > Science

0 answers

ANSWER

What is noble gas

Posted by Rashad Ahamed 7 years, 1 month ago

CBSE > Class 09 > Science

3 answers

Zainab Parwez 7 years, 1 month ago

Noble gas are those element whose outermost shell is full of 8 electron

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Sk Kumar 7 years, 1 month ago

It does not take part in any reaction

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Arpita Panwar 5 years, 11 months ago

Noble gas is a gas

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write application of Ultra sound

Posted by Vivek Gupta 7 years, 1 month ago

CBSE > Class 09 > Science

2 answers

Yogita Ingle 7 years, 1 month ago

Ultrasonic waves are used to capture the images of the heart and its features and problems associated with the heart, if any (for treatment purpose). This is called echocardiography.
Ultrasound scans/Ultrasonography are very commonly used to get images of internal body organs such as liver, kidney, uterus. It helps the doctor to diagnose and treat problems in the body of the patient. In this method, ultrasound waves are made to travel through the body to the organ under consideration. They get reflected and these are converted to electrical signals which can be monitored on a screen.
Ultrasonography is used to observe the growth of the fetus inside the uterus. It can also used to monitor the abnormalities.
It is used to break kidney stones into fine grains which later get flushed out through urine.

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Sarwadny Bhosale 7 years, 1 month ago

Sonar Echocardiography Clean the dust Sonography

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