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सी.आई.एस.सी.ई.आयसीएसई ICSE Class 7

Define : Atomic Number

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प्रश्न

 Define: Atomic number

व्याख्या
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उत्तर

Atomic number : Number of protons present in the nucleus of an atom.

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पाठ 4: Atoms, Molecules and Radicals - Additional questions

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सेलिना Concise Chemistry [English] Class 7 ICSE
पाठ 4 Atoms, Molecules and Radicals
Additional questions | Q 21.2

संबंधित प्रश्‍न

Write down the name of a compound represented by the following formula:

Al2(SO4)3


Write down the name of a compound represented by the following formula:

CaCl2


Write down the name of a compound represented by the following formula:

CaCO3


Give the name of the element present in the following compound:

Quick lime


Calculate the number of molecules of sulphur (S8) present in 16 g of solid sulphur.


Define: Atomic weight :


What is the atomicity of the following ?

  1. Oxygen
  2. Ozone
  3. Neon
  4. Sulphur
  5. Phosphorus
  6. Sodium

In what form does oxygen gas occur in nature ?


What is the difference between the molecule of an element and the molecule of a compound? Give one example of each.


One of the forms of a naturally occurring solid compound P is usually used for making the floors of houses. On adding a few drops of dilute hydrochloric acid to P, brisk effervescence are produced. When 50 g of reactant P was heated strongly, than 22 g of a gas Q and 28 g of a solid R were produced as products. Gas Q is the same which produced brisk effervescence on adding dilute HCl to P. Gas Q is said to cause global warming whereas solid R is used for white-washing.

  1. What is (i) solid P (ii) gas Q, and (iii) solid R.
  2. What is the total mass of Q and R obtained from 50 g of P ?
  3. How does the total mass of Q and R formed compare with the mass of P taken ?
  4. What conclusion do you get from the comparison of masses of products and reactant ?
  5. Which law of chemical combination is illustrated by the example given in this problem ?

What are (i) ionic compounds, and (ii) molecular compounds ? Give two examples of each type of compounds.


The cation of an element has :


Molecular compounds are usually formed by the combination between :


An element X forms the following compounds with hydrogen, carbon and oxygen :

H2X, CX2, XO2, XO3

State the three valencies of element X which are illustrated by these compounds.


Explain the term – molecules. Give three examples of atoms of the same element forming a molecule. State the atomicity of the same.


Give one example of a triatomic molecule


Give one example of a polyatomic molecule.


Give a reason why –

Ozone is considered triatomic, but phosphorus a tetratomic molecule.


State the atomicity of the following:

Oxygen


State the atomicity of the following:

Argon


State the atomicity of the following:

Sulphur


State true of false. If false, give the correct statement.

NaCl represents one molecule of sodium chloride.


Classify the following molecules as the molecules of element or compound

1.  
2.  
3.  
4.  

The Atomicity of phosphorous is ______


Define: Atomicity.


Derive the relationship between Relative molecular mass and Vapour density.


Which of the following contains maximum number of molecules?


Write any two classifications of a molecule.


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