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The matter is made up of indivisible particles known as atoms.
The properties of all the atoms of a given element are same including mass. This can also be stated as all the atoms of an element have identical mass; atoms of different elements have different masses.
Atoms of different elements combine in fixed ratios to form compounds.
Atoms are neither created nor destroyed. This implies that during chemical reactions, no atoms are created nor destroyed. The formation of new products (compounds) results from the rearrangement of existing atoms (reactants).

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What is difference between isobars and isotopes

Posted by Amrita Kumari 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 5 years, 8 months ago

Isobars	Isotopes
Chemicals elements which have the same mass	Different atomic structure of the same element
The atomic masses are equal	The atomic masses are different
Often the physical properties are similar	Usually, physical properties are different
Atomic numbers are different	Atomic numbers are the same
Chemical elements are different	same chemical elements but in different forms

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What are relation between the mole molecular mass &mass

Posted by Shiva Shukla 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Meghna Thapar 5 years, 7 months ago

The molecular mass of a substance is the sum of all the atoms present in one molecule of the substance.

It is expressed in atomic mass unit (u). However, mass is a measure of the amount of matter in an object.

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What are polyyatomic ions?

Posted by ???Priyanka Sood??? 5 years, 8 months ago

CBSE > Class 09 > Science

4 answers

Amrita Kumari 5 years, 8 months ago

A group of atoms carring a charge is known as polyatomic ions

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Kavya Bhatia 5 years, 8 months ago

The ions which are formed from groups of joined atoms are called polyatomic ions. They are also known as compousd ions. For example: SO42-, NH4+, etc.

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Yogita Ingle 5 years, 8 months ago

Polyatomic ions: Those ions which are formed from groups of joined atoms are called polyatomic ions.
Compound ions are also called polyatomic ions.

For e.g Ammonium ion NH⁴⁺, is a compound ion which is made up of two types of atoms joined together nitrogen and hydrogen.

Carbonate ion CO3²- , is a compound ions which is made up of two types of atoms joined together carbon and oxygen.

Similarly , sulphate ion SO4²-, Nitrate ion NO3^- , hydroxide ion OH^- e.t.c

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Shiwangi Bansal 5 years, 8 months ago

A group of atoms carring charge a single entity is known as polyatomic ions.

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What are the limitation of J.J thomson model and Rutherford model of atom

Posted by Aman Kumarjha 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 5 years, 8 months ago

Rutherford’s experiment was unable to explain certain things. They are:

Rutherford’s model was unable to explain the stability of an atom. According to Rutherford’s postulate, electrons revolve at a very high speed around a nucleus of an atom in a fixed orbit. However, Maxwell explained accelerated charged particles release electromagnetic radiations. Therefore, electrons revolving around the nucleus will release electromagnetic radiation.
The electromagnetic radiation will have energy from the electronic motion as a result of which the orbits will gradually shrink. Finally, the orbits will shrink and collapse in the nucleus of an atom. According to the calculations, if Maxwell’s explanation is followed Rutherford’s model will collapse with 10^-8 seconds. Therefore, Rutherford atomic model was not following Maxwell’s theory and it was unable to explain an atom’s stability.
Rutherford’s theory was incomplete because it did not mention anything about the arrangement of electrons in the orbit. This was one of the major drawbacks of Rutherford atomic model.

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Explain the characters of urochordata with examples

Posted by Abcd D 5 years, 8 months ago

CBSE > Class 09 > Science

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A sound wave of wave length is 0.332m has a time period 10-³ sec. If the time period is decreased to 10 - ⁴sec, determine the wave length and frequency of the new wave?

Posted by Dhanraj P 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Abhinav Panday 5 years, 8 months ago

Search on google

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How is weight of an object is related to its mass

Posted by Harnoor Sidhu 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Tishya Jha 5 years, 8 months ago

Weight of an object= acceleration due to gravity * mass of the object =>W= g*M => W= 9.8*M (g=acc. due to gravity=9.8ms^-2) (Let W=weight, M= mass)

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A body is covering equal distance directly proportional to the square of time. The acceleration of the body is - 1-constant 2-zero 3-increasing 4-decreasing Give appropriate reason......

Posted by Himanshu Singh 5 years, 8 months ago

CBSE > Class 09 > Science

0 answers

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Difference between mollusca and arthopoda

Posted by Harbindra Singh 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 5 years, 8 months ago

ARTHROPODA :-
------------------------

1)Body is divided into head, thorax and abdomen.

2)Body is covered by chitinous exoskeletons.

3) They have jointed appendages.

4)Excretion occurs through coxal gland on malpighian tubules.

5) Respiration occurs through tracheae or book lungs, e.g. prawn, cockroach.

MOLLUSCA:-
-------------------

1)Soft body divided into three distinct parts- a distinct head, visceral mass and muscular foot.

2)Body is covered by calcareous shell.

3)They have distinct foot for moving around.

4)Excretions occurs through nephridia.

5) Respiration occurs through gills .

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ch 4

Posted by Ansh Waliya 5 years, 8 months ago

CBSE > Class 09 > Science

0 answers

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What is the scientific name of phanerogams

Posted by Nirmal Singh 5 years, 8 months ago

CBSE > Class 09 > Science

2 answers

Jish Reddy 5 years, 8 months ago

The spermatophytes, also known as phanerogams (taxon Phanerogamae) or phaenogams (taxon Phaenogamae), comprise those plants that produce seeds, hence the alternative name seed plants.

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Shubham Meena 5 years, 8 months ago

Spermatophyta

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Havana gatkonu algikarn

Posted by Mahesh Patel 5 years, 8 months ago

CBSE > Class 09 > Science

0 answers

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Which device is used to measure boling water temperature

Posted by Abhi Nandan 5 years, 8 months ago

CBSE > Class 09 > Science

3 answers

Jish Reddy 5 years, 8 months ago

A thermometer is an instrument that measures temperature. It can measure the temperature of a solid such as food, a liquid such as water, or a gas such as air. The three most common units of measurement for temperature are Celsius, Fahrenheit, and kelvin.

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Nirmal Singh 5 years, 8 months ago

Thermometer

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Mahesh Patel 5 years, 8 months ago

Burnar

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what is wave motion??

Posted by Diya Mundra 5 years, 8 months ago

CBSE > Class 09 > Science

2 answers

Yogita Ingle 5 years, 8 months ago

Wave motion is the transfer of energy and momentum from one point of the medium to another point of the medium without actual transport of matter between two points. Wave motion is classified into three different ways they are,

The medium of propagation,
The dimensions in which a wave propagates energy,
The energy transfer

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Nirmal Singh 5 years, 8 months ago

Transversal wave

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How a change in temperature had the effect on water pollution?

Posted by Riya Pihu 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Meghna Thapar 5 years, 7 months ago

Increase in temperature leads to global warming and also reduces concentration of oxygen in water bodies. High temperature also affects the aquatic organisms because each organism has an optimum temperature in which they can live. Increase in temperature influences several other parameters and can alter the physical and chemical properties of water.

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What is jj Thomson theory

Posted by Sanmegh Chavan 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Nirmal Singh 5 years, 8 months ago

JJ Thomson theory state that in a atom all space most of the all space are empty and electrons are embedded in it like a pudding by example of watermelon in a watermelon in the part eating is the positive area and the seeds of watermelon embeddedin are the electrons

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What is rutherford model of an atom

Posted by Devashish Singh 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Nirmal Singh 5 years, 8 months ago

Rutherford model state that in atom most of the space are empty and the mass of the atom are in the centre called the nucleus

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Why evaporation causes cooling effect ?

Posted by Vassu Yadav 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Shivansh Mishra 5 years, 8 months ago

During evaporation process the particles of liquid gain energy from their surroundings in order to overcome the force of attraction between them. This causes loss of heat energy in the surroundings that is why evaporation causes cooling.

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defination of vector in chaptrr why do we fall ill

Posted by Simran Simran 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Rajamani Gopinath 5 years, 8 months ago

Vector r insects which transmit diseases

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What is the difference between isobars and isotopes

Posted by Amrita Kumari 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Krish Aggarwal 5 years, 8 months ago

Isotopes have the same atomic number, while isobars have the same atomic mass. Isotopes : Isotopes are atoms that have same atomic number but different mass numbers. Isotopes have the same atomic number because the number of protons inside their nuclei remains the same.

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Name the process by which a pure solid can be separated from solution in crystal form

Posted by Ayan Master 5 years, 8 months ago

CBSE > Class 09 > Science

3 answers

Shubham Meena 5 years, 8 months ago

Crystallisation

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Jaspreet Kaur Sandhu 5 years, 8 months ago

Crystallisation

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Yogita Ingle 5 years, 8 months ago

Crystallisation is a process used to separates a pure solid in the form of its crystals from a solution.

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Naphthalene ball disappear with time without leaving any residue

Posted by Prishthi Verma 5 years, 8 months ago

CBSE > Class 09 > Science

4 answers

Krish Aggarwal 5 years, 8 months ago

because they undergo sublimation i.e., they directly change into vapour without passing through the liquid state. ... The perfumes contain solvent which carries pleasant smelling vapour

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Anshika Mishra 5 years, 8 months ago

Because there sublimation process

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Rakshit Yadav 5 years, 5 months ago

Very bad answer given by Yogita Ingle

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Yogita Ingle 5 years, 8 months ago

Naphthalene balls disappear with time without leaving any solid because they undergo sublimation i.e., they directly change into vapour without passing through the liquid state.

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Define coelom and triploblastic

Posted by Mayank Alwani 5 years, 8 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 5 years, 8 months ago

Triploblastic: In an animal body, during the formation of embryo, germ layers are formed. Animals that have three germ layers; endoderm, exoderm and mesoderm are said to be triploblastic.

Coelomic cavity: Coelomic cavity or coelom is the fluid-filled cavity where the internal organs remain suspended. It is formed within the mesoderm layer of the embryo during the development of organisms. Coelom absorbs shocks and allows the muscles to grow independently.

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How to create a table in ms excel?

Posted by Partha Das 5 years, 8 months ago

CBSE > Class 09 > Science