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सी.आई.एस.सी.ई.आयसीएसई ICSE Class 7

Define : Mass Number : - Chemistry

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प्रश्न

Define: Mass number : 

व्याख्या
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उत्तर

Mass number : Numbr of protons and neutrons 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 21.3

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:

KNO3


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


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

Hydrogen bromide


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

Baking powder


Define: Atomic number


Define: Atomic weight :


What is meant by atomicity ? Explain with two examples.


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 ?


In what form do noble gases occur in nature?


What do the following denote ?

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

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


Molecular compounds are usually formed by the combination between :


An element A forms an oxide A2O5.

What is the valency of element A ?


Calculate the mass of 3.011 × 1024 atoms of carbon.


Why are the symbols and formulae of substances important?


State the main points of the contradiction of Dalton’s atomic theory by the Modern Atomic Theory.


Give a reason why –

Helium is considered monoatomic, but hydrogen a diatomic molecule.


Give a reason why –

Ozone is considered triatomic, but phosphorus a tetratomic molecule.


State the atomicity of the following:

Neon


State the atomicity of the following:

Sulphur


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


Two elements sometimes can form more than one compound.


Give any two examples for heterodiatomic molecules.


Write any two classifications of a molecule.


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