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सी.आई.एस.सी.ई.आईसीएसई ICSE Class 7

Define Number - Chemistry

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प्रश्न

Define: Atomic number

परिभाषा
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उत्तर

Atomic number— Atomic number refers to the number of protons present in an atom. It is denoted by Z.

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अध्याय 4: Atoms, Molecules and Radicals - Additional questions

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सेलिना Concise Chemistry [English] Class 7 ICSE
अध्याय 4 Atoms, Molecules and Radicals
Additional questions | Q 1.3

संबंधित प्रश्न

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

CaCl2


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

Quick lime


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

Hydrogen bromide


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

Potassium sulphate


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


 Define: Atomic number


Define: Mass number : 


Define: Atomic weight :


What is meant by atomicity ? Explain with two examples.


In what form do noble gases occur in nature?


What do the following denote ?

  1. N
  2. 2N
  3. N2
  4. 2N2

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 ?

Work out the formula for magnesium hydrogencarbonate.


The cation of an element has :


Molecular compounds are usually formed by the combination between :


An element A forms an oxide A2O5.

What is the valency of element A ?


Correct the following statement:

A molecule of sulphur is monoatomic.


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


State the atomicity of the following:

Neon


State the atomicity of the following:

Chlorine


State the atomicity of the following:

Argon


Classify the following molecules as the molecules of element or compound

1.  
2.  
3.  
4.  

If a molecule is made of similar kinds of atoms, then it is called ______ atomic molecule.


The Atomicity of phosphorous is ______


Which of the following contains maximum number of molecules?


Write any two classifications of a molecule.


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