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What is a chemical reaction? - Chemistry

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प्रश्न

What is a chemical reaction?

लघु उत्तर

उत्तर

A chemical reaction is the process of breaking the chemical bonds of the reacting substances (reactants) and making new bonds to form new substances (products).

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पाठ 2: Chemical Changes and Reactions - Exercise 2 (A) [पृष्ठ २३]

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सेलिना Concise Chemistry [English] Class 9 ICSE
पाठ 2 Chemical Changes and Reactions
Exercise 2 (A) | Q 1.1 | पृष्ठ २३

संबंधित प्रश्‍न

MULTIPLE CHOICE QUESTIONS

Tick the most appropriate answer.

 

Miscible liquids having slightly different boiling points can be separated by the

  1. evaporation
  2. distillation
  3. fractional distillation
  4. sedimentation

FILL IN THE BLANK

In a double decomposition precipitation reaction both the reactants must be ............ soluble.


What are biocatalysts ?


Define chemical 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)

Chlorine (Cl2) molecule is formed by ______ of electrons between two chlorine atoms.


Explain by writing a word equation.

Limestone powder disappears on adding to dilute hydrochloric acids.


Give an example of the following chemical change.

Two solids combine to form a liquid


State the main characteristics of chemical reactions. Give at least one example in each case.


State the original colour of the following substance and colour of residue obtained after heating.

Zinc carbonate


Give a chemical test to distinguish between the following gases. 

SO2 and Cl2 


Distinguish by heating the following in dry test tubs.

Ammonium Chloride and iodine.


On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.

A white solid which evolves two colourless gases which on cooling combine and condense on the cooler parts of the test tube.


The percentage composition of Nitrogen in Ureas is ______.


On heating calcium carbonate gets converted into calcium oxide and carbon dioxide.

(a) Is this a physical or a chemical change?

(b) Can you prepare one acidic and one basic solution by using the products formed in the above process? If so, write the chemical equation involved.


Heat may evolve or be absorbed during a ______ change.


Galvanization is a process in which ______ is coated as a layer of iron.


Explain how the painting of an iron gate prevents it from rusting.


______ is the chemical name of slaked lime.


What is thermochemical reactions?


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