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सी.आई.एस.सी.ई.आयसीएसई ICSE Class 7

Explain the Term ‘Chemical Reaction’ with Special Reference to – ‘Reactants’ and ‘Products’. - Chemistry

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प्रश्न

Explain the term ‘chemical reaction’ with special reference to – ‘reactants’ and ‘products’.

एका वाक्यात उत्तर

उत्तर

A chemical reaction involves the breaking of existing bonds between atoms or groups of atoms of the reactants and leading to formation of new bonds forming new substances called the products.

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पाठ 5: Language of Chemistry - Exercise

संबंधित प्रश्‍न

When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.


TRUE \ FALSE

Weak electrolytes dissociate partially in their aqueous or fused state.


Fill in the blank:

In some chemical reactions an insoluble ________ is formed when two solutions are mixed.


Write true or false  :
No new substance is formed during a chemical reaction.


Write true or false  : 

Hydrogen sulphide has rotten egg smell .


Write true or false.

A chemical equation gives only qualitative information of a chemical reaction.


Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
To prevent rusting, a layer of ______ metal is applied on iron sheets.


Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.

(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)

Rusting of iron is a ______ chemical change. 


Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.

(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)

Oxygen is a ______ in respiration.


Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.

Hydrogen chloride


Give reason for the following:

Silver nitrate solution is kept in coloured bottles.


When hydrogen burns in oxygen, water is formed; when electricity is passed through water, hydrogen and oxygen are given out. Name the type of chemical change involved in the two cases.


What do you observe when H2S is passed through a lead nitrate solution.


A chemical reaction is often accompanied by external indications or characteristics which include – 

  1. Colour change
  2. Effervescence or gas evolved
  3. Evolution or absorption of heat
  4. Formation of a precipitate.

With reference to each of the above indications, state the external indication seen during – Addition of dilute hydrochloric acid to silver nitrate.


A chemical reaction is often accompanied by external indications or characteristics which include – 

  1. Colour change
  2. Effervescence or gas evolved
  3. Evolution or absorption of heat
  4. Formation of a precipitate.

With reference to each of the above indications, state the external indication seen during – Addition of water to quicklime.


Give balanced equation for the following conversion affected by heat alone on the substance:

Hydrated copper sulphate to sulphur dioxide


Complete the table given below.

Heat on  Zinc nitrate Colour of residue  

Select the correct answer from the options given below:

State the gaseous product formed, when

An active metal reacts with dilute sulphuric acid.


Differentiate between the following:

Neutralization reaction and a precipitation reaction.


NPK are the primary nutrients for plants.


The chemical change is ______.


Burning of paper is a ______ change.


The percentage composition of Nitrogen in Ureas is ______.


The water we drink is a combination of hydrogen and oxygen.


Write some materials prepared by chemical changes.


Which of the following are chemical changes?

(i) Decaying of wood

(ii) Burning of wood

(iii) Sawing of wood

(iv) Hammering of a nail into a piece of wood


A chemical change may involve –


A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.

What changes do you expect?


A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.

Write a word equation for the chemical change, if any.


How can we prevent rusting?


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