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सी.आई.एस.सी.ई.आईसीएसई ICSE Class 7

State Four Conditions Necessary for Chemical Reactions to Take Place. - Chemistry

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प्रश्न

State four conditions necessary for chemical reactions to take place.

एक पंक्ति में उत्तर

उत्तर

Conditions necessary for chemical reactions :

  1. Close contact
  2. Solution form
  3. Heat
  4. Light
  5. Catalyst
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अध्याय 5: Language of Chemistry - Exercise

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सेलिना Concise Chemistry [English] Class 7 ICSE
अध्याय 5 Language of Chemistry
Exercise | Q 2

संबंधित प्रश्न

 What are (i) positive catalysts and (ii) negative catalysts? Support your answer with one example for each of them.


 Fill in the blank.
 The formation of gas bubbles in a liquid during a reaction is called ......................


TRUE \ FALSE

Ammonia is a good oxidizing agent.


TRUE \ FALSE

Evaporation of water is a physical change. True or false ?


Name three reducing agents ?


Explain the type of reactions on the basis of the direction of reaction.


What do you observe when :

an iron nail is kept in tap water for few days


Write true or false  : 

Hydrogen sulphide has rotten egg smell .


Explain the following reaction with one suitable example of Combination reactions .


Explain the following reaction with one suitable example of Double decomposition reaction.


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)

The spoiling of food is a chemical change which is recognized from the generation of certain ______ due to it.


Give an example of a reaction where the following are involved

Pressure


Complete and balance the following reaction:

NaCl(aq) + AgNO3(aq) →


Name: Two carbonates do not produce carbon dioxide on heating.


Name: Gas with rotten egg smell. 


Write your observation and a balanced equation in the case of the following substances being heated.

Ammonium dichromate.


Give a word equation for the following reaction.

A salt which reacts with ammonium hydroxide to give a reddish brown precipitate.


Name the following:

The products obtained during ‘photosynthesis’ – which is a chemical change.


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

Copper nitrate to nitrogen dioxide


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

Ammonium dichromate to nitrogen


Complete the table given below.

Addition of dil. H2SO4 to FeS  Odour of gas evolved  

A chemical reaction is often accompanied by external indications or characteristics.


Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.

Lead nitrate.


________ is a chemical substance which alters the speed of a chemical reaction.


Mention the various conditions required for a chemical reaction to occur.


Rusting of Iron: undesirable change:: Dead plants turn into manure: ______.


Water boiling into water vapour is an example of chemical change.


Write some materials prepared by chemical changes.


Iron benches kept in lawns and gardens get____________. It is a _________ change because a new _________ is formed.


Acid rain is a result of ______.


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