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सी.आई.एस.सी.ई.आयसीएसई ICSE Class 7

Define Number - Chemistry

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प्रश्न

Define: Atomic number

व्याख्या

उत्तर

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

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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 1.3

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:

CaCl2


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

KNO3


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.


State the term.

The number of atoms present in a molecule of an element _________


 Define: Atomic number


Define: Atomic weight :


Write the formulae of the following compounds. Also name the elements present in them.

  1. Water
  2. Ammonia
  3. Methane
  4. Sulphur dioxide
  5. Ethanol

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.


Work out the formula for magnesium hydrogencarbonate.


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


An element A forms an oxide A2O5.

What is the valency of element A ?


Calculate the mass of 3.011 × 1024 atoms of carbon.


Give one example of a triatomic molecule


Give one example of a polyatomic molecule.


Give a reason why –

Helium is considered monoatomic, but hydrogen a diatomic molecule.


State the atomicity of the following:

Chlorine


Which of the following is a short and scientific way of representing one molecule of an element or compound?


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 ______


Two elements sometimes can form more than one compound.


Derive the relationship between Relative molecular mass and Vapour density.


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