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प्रश्न
Explain the term ‘chemical reaction’ with special reference to – ‘reactants’ and ‘products’.
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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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संबंधित प्रश्न
Changes in which new substances are formed are called ______ changes.
Give one example that illustrates the following characteristics of a chemical reaction:
Change in state
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In a double decomposition precipitation reaction both the reactants must be ............ soluble.
State four conditions necessary for chemical reactions to take place.
Give an example of a reaction where the following are involved
Catalyst
Write the chemical reaction where the following changes are observed.
Precipitate is formed
What do you observe? When
Sodium chloride solution is added to silver nitrate solution.
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- 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.
State the following reaction represent oxidation or reduction.
\[\ce{Cl- ->Cl}\]
State the following reaction represent oxidation or reduction.
\[\ce{Cu++->Cu}\]
Give a suitable example with an equation to show the representation of a chemical reaction.
NPK are the primary nutrients for plants.
Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B). The following statements pertain to these changes. Choose the correct one.
Match the following:
| 1. | Sodium Chloride | a. | CaSO41/2H2O |
| 2. | Calcium sulphate dihydrate | b. | C2H5Oh |
| 3. | Magnesium sulphate hydrate | c. | CaSO4.2H2O |
| 4. | Calcium sulphate hemihydrate | d. | NaCl |
| 5. | Phenol | e. | MgSO4.H2O |
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.
Melting of wax is a change where a solid changes to liquid state. Give one more such change which you observe in your surroundings
Iron benches kept in lawns and gardens get____________. It is a _________ change because a new _________ is formed.
Give an example of a chemical reaction for the following situation:
A change in colour is observed
Write the equation for the process of formation of rust.
______ is a chemical substance is used in whitewashing.
